missing "And"  -- (MW) The untranslated word "and" is used as the conjunction "and," but it also is used to add emphasis ("also") and, In a series, it is can be translated as "not only...but also." Here, the two are used together to have the "not only...but always" sense.

All - The word translated as "all" is from the Greek adjective meaning "all," "the whole," "every," and similar ideas. When it is used as a noun, we would say "everything." As an adverb, it means "in every way," "on every side," and "altogether."

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. 

nations: -- The word translated as "nations" means "a group of people living together," a nation, a tribe, or a cast of people. Later it came to mean "barbarous nations" similar to our idea of ethnic people. Jesus used it to mean "non-Judean" people.

will-- This helping verb "will" indicates that the verb is the future tense. Helping or auxiliary verbs are needed to translate the Greek verb forms into English.-- This helping verb "shall" indicates that the verb is the future tense. Helping or auxiliary verbs are needed to translate the Greek verb forms into English.

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.

gathered  - The Greek word translated as "gathered" means "to bring together." It has many different uses but Christ uses it to mean "bring together."

before -- The Greek word translated as "before" means "in front of" referring to place and when used to apply to time means "beforehand."

him -- The word translated as "him" is the Greek word commonly translated as third-person pronouns in English.

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

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

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

separate  - "Separate" is a Greek verb that means "to mark off boundaries," "to determine," and "to separate" in the sense of "distinguish" as well as "to banish." "Separate" works best here because the object is sheep and goats.

the people -- The word translated as "the people" is the Greek word commonly translated as third-person pronouns in English. Here the form is "them." However, it masculine so it indicates people rather than the nations themselves.

one -- The word translated as "one...another" is allelon, which means "one another," "to one another," "mutually," and "reciprocally." This word appears after the preposition "from."

from -- The word translated as "from" means "from" in both locations and when referring to a source or a cause.

another, -- This completes the idea of the earlier word.

as -- The Greek word translated as "as" indicates a match with a person or thing.

a -- (WW) 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. 

shepherd  - "Shepherd" is a Greek word that means "herdsmen," "shepherd," and, generally, "captain," and "chief."

separates --  "Separates " is a verb that means "to mark off boundaries," and "to separate" in the sense of "distinguish" as well as "to banish."

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. 

sheep  - "Sheep" is Jesus's symbol for his followers. The Greek word refers to any domesticated animal and works better if translated simply as "flock" or "herd." The flock follows the shepherd, which is above them. It is also together, a united group.

from -- The word translated as "from" means "from" in both locations and when referring to a source or a cause.

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. 

goats: -- "Goat" is from a word, meaning "young goat" or "kid," that Christ uses only twice, here and in Luke.