I  -- This is from the first-person, singular form of the verb.

will -- (WT) This helping verb "will" indicates the future tense, but the verb is not the future.

ask   -- (CW) The word translated as "ask" means "consult," inquire of," and "ask." It is used extremely commonly in the narrative parts of the NT, but Jesus the word rarely. Jesus usually uses another Greek word for this common idea.  Here, this word is used twice with Caiaphas and Pilot, when he is being "interrogated.," which is the best translation for how Jesus uses it. This is not the word usually translated as "ask."

you -- The "you" here is the second-person, plural pronoun in the form of an object of the action or preposition. As the object of a preposition, an accusative object indicates movement towards something or a position reached as a result of that movement.

one thing; -- (OS) There is nothing in the Greek that can be translated as "one thing" in the source we use today but it does exist in the source that the KJV translators used. In today's source this word is the "if/whether" that expresses a condition but it means nothing regarding whether that condition It also means "if ever," "in case," and "whenever" when citing a possibility.  It also means "if ever" and "whenever." When citing a fact  instead of a possibility, the sense is more  "whether," "since" or "as sure as."

is -- This helping verb indicates the present tense of the verb. It is used here to form the present, progressive tense, which doesn't exist in Greek but which can smooth the flow of English sentences.

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

lawful: -- (CW) "Lawful" is a verb, which means "it is possible" and "it is allowed." It generally refers to something within someone's power, or, in this case with the negative, something outside of someone's power. This word does not, as it might seem, refer directly to Biblical law. This translation is more specific than the word's meaning.

on  -- This word "on" comes from the dative case 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.  

the   -- The word translated as "the" is the Greek definite article; without a noun, it has the sense of "the one." The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," "those") than the English "the." See this article for more. 

sabbath  The word translated as "sabbath" is the Greek version of the Hebrew word "shabbat" meaning "rest" or "day of rest".  

to -- This "to" is added because the infinitive form of the verb requires a "to" in English.

do good -- The verb translated as "to do good" means "to do good", "to do well", "to act rightly," and "to exert a beneficial influence." It combines the verb meaning "to make" or "to perform" with the common Greek adjective meaning "useful", "worthwhile," and "of high quality." See this article on "good" and this one on "evil."

or "Or" is translated from a Greek word that means primarily "or" but serves as "than" in a comparison.

to -- This "to" is added because the infinitive form of the verb requires a "to" in English.

do evil: The verb translated as "to do evil" means "to do ill", "to play the knave," and "to do mischief," and "to injure." It combines the verb meaning "to make" or "to perform" with the common Greek adjective meaning many different forms of "bad," including "ugly", "low born", "craven," and "ill." In the NT, it is often translated as "evil." More about it in this article.

to -- This "to" is added because the infinitive form of the verb requires a "to" in English.

save -- "Save" is the Greek word that means "to keep alive" when applied to people or "to keep safe" when applied to things. Jesus uses it to mean "rescue" in most cases.

life -- (CW) The word translated here as "life" is psyche, a common word in Greek, familiar in English, meaning "life," "soul," "consciousness," and "a sense of self." It is used for different aspects of "self," the emotional self, the conscious self, the intellectual self. It has a clear sense of the conscious self and is often translated as "life" in the Gospels. Jesus uses it to specifically mean our identity in our worldly life, the role we play on earth, what we might call the "social self," or what we commonly call our "ego." Since "life" is commonly translated from another Greek word. When "self" doesn't work, "person" offers less confusion. See this article for detail about this word.

or: "Or" is translated from a Greek word that means primarily "or" but serves as "than" in a comparison.

to -- This "to" is added because the infinitive form of the verb requires a "to" in English.

destroy - -- The word translated as  "kill" to "destroy" or "demolish" and can be "perish" in the passive. However, it can also mean to "lose" things. Its literal meaning from its root is "destroy from" or "ruin from." It is often used in the middle voice to describe people losing or destroying themselves. This is not the common word for "kill," which is used in the parallel of this verse.

it - - There is no Greek pronoun here, but Greek does not need pronouns when the object can be assumed from the context. In English, they are added for the subject-verb-object form of our sentences.