But -- The Greek word translated as "but" means "but," "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.  It can also be an explanation of cause ("so"). When used with a conditional starting a clause, the sense is "if/when...then."

the-- (IW) There is nothing that can be translated as "the" in the Greek source.  While sometimes a "the" should be added in English before plural words, this phrase makes a better translation without it.  Especially if the following word is translated more accurately.

time - -- (WN) The Greek word translated as "days" means "day," "time," in general, and refers specifically to the "daytime." However, because this word is plural, it works better as "days."

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.

come, -- The word translated as "come" 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.

when -- The Greek word translated as "when" introduces a phrase that explains a certain condition so "whenever" or "since."

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. 

bridegroom - The word translated as "bridegroom" is a male form of the adjective meaning "bridal," hence, "groom" or "son-in-law."

will -- (CW) This helping verb "will" does not indicate the future tense, but that the verb describes a possibility, the subjunctive voice. A "might" or "should" in English is more appropriate, but is assumed in an "if/when/whoever/except" clause. Helping verbs are not needed in Greek since the main verb carries this information in its form.

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.

taken -- The term translated as "shall be taken" means "to lift off", "to carry off," and "to lead away." It is in the passive form, but is not the future tense. It is in a form indicating something that might happen.

from - --- ( The word translated as "from" means "from" in both locations and when referring to a source or a cause. It also means the instrument "by" which a thing is done and "away from."

them, -- The word translated as "their" is the Greek adjective that acts like our third-person pronoun. The form is the third person, plural in the genitive form. It is used as a possessive or the object of a verb or preposition.  As a preposition's object means a movement away from something or a position away from something else. This pronoun follows the noun so "of theirs."

and -- The Greek word translated as "and" is used as the conjunction "and," but it also is used to add emphasis ("also"). In a series, it can be translated as "not only...but also." After words implying sameness "as."

missing "then"  -- (MW) The untranslated word  MW - Missing Word -- The word "then" is not shown in the English translation. "then" means "at this time" or "then." With the subjective negative, the sense is "not when."

on -- The word translated as "in" means "in," "within," "with" (an instrument), "by" (near), "by" (means of), "during" (time),  or "among"  with a dative object as the one here.  With the accusative, it means "into," "on," and "for." When referring to time, it means "during." It can mean "on," "at," or "by" in the sense of "near."

that -- (CW) The word translated as "that " is an adjective that highlights its noun as being in a specific place or time from a word that means "there." Used a pronoun, the sense is "that one there" or "this one here." Jesus often uses it as a term of honor to refer to his father, the Spirit, prophets, and so on.

missing "the/this"  -- (MW) The untranslated word is the Greek definite article," the," which usually precedes a noun and, without a noun, takes the meaning of "the one." The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," and "those"). See this article for more. 

day. -- The Greek word translated as "day" also means "time," in general, and refers specifically to the "daytime."

they -- This is from the third-person, plural form of the verb.

will --  This helping verb "will" indicates that the verb is the future tense but the form could also indicate a possibility at some time. A "might" or "should" could work here or nothing at all in an "if/when" clause which implies a possibility.  Helping or auxiliary verbs are needed to translate the Greek verb forms into English.

fast - The term translated as "fast" specifically means a religious fast. It also means "to abstain from" when it has a genitive object.