But -- The Greek word translated as "but" means "but," "yet," "however," and "on the other hand." It joins phrases in an adversarial way. Since it always falls in the second position, translating it as "however" often captures its feeling better.  This word doesn't mean "and." 

understand , -- (WW) "Understand " is a verb that means  "to learn to know,""to know," "to recognize," "make known," "to know carnally," and "to learn." The idea of "learn" seems to translate this word better so it isn't confused with the verb meaning "have seen" which is also used to mean "know." This verb is more versatile because it can be used in more tenses. This word doesn't mean "understand." 

this -- (CW) The word translated as "this" means "from here" "from there" or "this/that thing/person here/there." As a pronoun by itself, it means "this here" but it can be shortened to just "this."  The Bible usually translates it as the adjective "this" when it appears after words modifying them, which is confusing because the definite article, with which it is often used before the word, also can mean "this." It works better as "here," which is how Jesus usually uses it, but it can also mean "there." It often comes after the noun, emphasizing it, "this thing here."

missing "that"  -- (MW) The untranslated word   "that" introduces a statement of fact or cause, "for what," "because," "since," "seeing that," "that," and "wherefore." Jesus usually uses this word to mean "because" in statements that seem like an answer to a question because of the change of context. It means "because" when answering a "why" question and "that" when explaining a "what" question. Another common word is used for "for."

If -- The "if" here is used to express conditions "if" (implying nothing about its fulfillment) or indirect and direct questions, "whether."It also means "if ever" and "whenever." When used in an "if" clause, the verb is the subjunctive form of possibility. However, this verb doesn't have a subjunctive form and it only works as if.

the   -- The word translated as "the" is the Greek definite article, "the," which usually precedes a noun or changes the word it precedes (adjective, infinitive, participle, etc.) to act like a noun. The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," "those") than the English "the." See this article for more. 

owner of the house -- "Goodman of the house" is from a compound Greek word that is literally the "master of the house." It was translated as "householder."

had -- This helping verb "had" indicates that the verb is the tense indicating an action completed in the past.

known  -- The word translated as "know" means primarily "to see" and is used to mean "know' as we use the word "see" to mean "know" in English. It is the past perfect tense so "have seen" but it is translated as the present tense of "know."  What someone "has seen" is what they "know" in the present.

at -- This word "at" comes from the indirect object form of the following word that requires the addition of a preposition in English. The most common is a "to" for the English indirect object. However, the translator can choose other prepositions: "with,"  "in,"   "of,"  "as," "by," "for," "at," or "on" depending on the context.

what -- The Greek word translated as "what" means "of what kind," "whose," "what," and "which."

hour   - The word translated as "hour" means a period of time equal to the one-twelfth part of the daylight, like an "hour." More generally, it means a period of time, like a "season."

the -- The word translated as "the" is the Greek definite article, "the," which usually precedes a noun or changes the word it precedes (adjective, infinitive, participle, etc.) to act like a noun. The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," "those") than the English "the." See this article for more. 

thief - "Thief" is from the Greek noun that means "thief," "cheat," and "knave."

was --  This helping verb indicates the past tense of the verb.

coming, --  --  The word translated as "coming" primarily means "to start out" but Christ usually uses it to mean "come" but not always. It indicates movement, especially its beginning, without indicating a direction toward or away from anything, so it works either as "start," "come," or "go," but it is more like our phrase "being underway." Our English word "show up" captures both the "start" and "come" ideas. See this article for more.This is the past, progressive tense, which doesn't exist in Greek but it  can smooth the flow of English sentences. This would be better as "came."

missing "himself" -- (MV)  The middle voice of the verb indicates that the subject does something to, for, or by themselves.

he -- This is from the third-person, singular form of the verb.

would -- (WM) The verb "would" is indicates a mood of possibility, this is a simple statement.

he -- This is from the third-person, singular form of the verb.

would -- "Would" is a particle used with verbs to indicate that the action is limited by circumstances or defined by conditions. There is no exact equivalent in English but "possibly" is close. This word works similarly to the "might" or "should" of a subjunctive verb, but we don't want to confuse it with the subjunctive so using "possibly" provides a consistent translation.  This particle usually suggests the subjunctive form of the verb but can be used without it.   Its meaning is largely determined by the verb form but "would have" is the most common, even when not with a subjunctive verb. The same Greek letters can always be the more common conjunction meaning "when," so this meaning comes from context.

watched missing "watched "  -- (MW) The untranslated word  -- means "to be or to become fully awake." In English, we would say "wake up" to someone sleeping and "stay awake" to someone already awake. It comes from a common Greek word that means "awaken" but is usually confusingly translated as "arise."

and -- The Greek word translated as "and" is used as the conjunction "and," but it also is used to add emphasis, "even," "also," and "just."

not -- The Greek word translated as "not" is the Greek negative used to deny objective facts, not opinions. It means "no," "not," or"no truly." It makes a negative statement of fact. When a negative precedes the verb, it affects the whole clause. When it precedes other words, its force is limited to those words. 

have -- (WT) This helping verb "have" indicates that the verb is the tense indicating an action completed in the past. This is not the tense of the verb here.

let -- The word translated as "let" primarily means "to let go," "to leave," "let loose," or "to send away."  It can also mean "remit" a debt or "excuse" a fault. It has the sense of leaving something alone and letting it drop. See this article for more.

his - The word translated as "his" is the Greek word correctly translated as third-person "his/him" in English.  The word appears after the noun so the sense is "of his." - In its adverbial form, this means "just here" or "exactly there." 

missing "the/this"  -- (MW) The untranslated word is the Greek definite article," the," which usually precedes a noun or changes the word it precedes (adjective, infinitive, participle, etc.) to act like a noun. The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," and "those"). See this article for more.

house --  - The Greek word translated as "house," refers to the building itself, all the people that dwell in it, including slaves and servants, all property owned by that family, and all the descendants of the continued line. Since the masculine form works better as "house," this might work better as home.

be -- This helping verb "be" indicates that the verb is passive. Helping or auxiliary verbs are needed to translate the Greek verb forms into English.

broken -- (CW,WF) "Broken" is from a verb that means  "to dig through" and, metaphorically, "undermine" and "ruin." It doesn't mean "broken." This is not an active verb but an infinitive. 

into. - (CW) This completes the meaning of the verb. It is from the prefix. This is not the prefix usually translated as "into."