Verily -- The word translated as "verily" is from the Hebrew word that means "truly" or "certainly", but it sounds like the Greek word with the same meaning. In Greek, the word also means "to reap". See this article discussing this "amen phrase.".

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

say -- The word translated as "say" is the most common word that means "to say" and "to speak", but it also means "to teach", which seems to be the way Christ uses it more frequently. It also has many ancillary meanings such as "to count" ("to number" or like we might say, "to recount" a story) or "to choose for yourself". Christ usually uses this word to refer to his own speaking or teaching. The form of the verb could also be a possible action, "might say" or "should say".

unto -- This word "unto" comes from the dative case of the following word that requires the addition of a preposition in English, but the translator must decide which preposition to use: a "to" as an indirect object.

you,  -- The Greek pronoun "you" here is plural and in the form of an indirect object, "to you", "for you", etc.

missing "when" -- (MW) The untranslated word  when" because it indicates more of an expectation of something happening than "if" alone.  It can be used after a demonstrative pronoun to mean "that possibly", "whosoever" or "whatsoever".

This - 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. 

generation -- The word translated as "generation" means "race", "family" and "generation". Christ uses this term frequently in criticism, but that criticism seems more aimed at a certain type of person, or, more narrowly, a certain group among his own people, than it is his generation as we used the term. It is the word from which we get the scientific "genus".

missing "itself"  -- (MW) The untranslated word "itself" is the Greek word commonly translated as third-person pronouns in English. The form is the singular subject of the sentence, and it is feminine. Since Greek active verbs include the singular form of the subject, when the subject is clear, this pronoun can be repetitive, emphasizing the subject. This is how we say "itself" to emphasize the subject.  

shall -- (CW) This helping verb "shall" 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. 

not .-- (CW) The "not" here is both of the Greek negatives used together. Greek has two negatives, one objective, one subjective. The use of both together is more extreme, like saying, "never" or literally, "you cannot really think". When a negative precedes the verb, it affects the whole clause. When it precedes other words, its force is limited to those words. 

 pass away -- The phrase "pass away" is from a verb that means "go by", "pass by", "outstrip" (in speed), "pass over", "outwit", "past events" (in time), "disregard" and "pass without heading".  The sense here could be "pass by" or "surpass", but the sense of "pass away" as in "die" is not at all clear. The word means to pass the time and can refer to times past, but it also means to "outwit" and "elude" and "be superior". It also means to "pass by" a place or to "arrive" at a place. In the Latin Vulgate, this verb was translated as "transit" which is the future, plural, active form of the word that means "to cross". The form is not the future tense, as translated, but in a form that means something is possible. This idea is emphasized by a word that appears in some good Greek sources, but which is not translated in the KJV.

till --  The word translated as "until" means "until" but it also means "in order that".

all  - The word translated as "all" is the Greek adjective meaning "all", "the whole", "every" and similar ideas. When it is used as a noun, we would say "everything".

be -- (WV) This helping verb "be" seems to indicate that the verb is passive but it isn't. It is a verb form that indicates the subject is acting on itself.

fulfilled -- (WW) The word translated as "shall come to pass" means "to become" and "to happen", that is, to enter into a new state. In Greek, especially as used by Jesus, it is the opposite of "being". which is existence in the current state. It is also not in the future tense, but the form that indicates something that might happen. Since it refers to events, the sense is "happen". The form is that of things acting on themselves, which is captured by our word "happen", which doesn't suggest an outside force. This word doesn't mean "fulfilled".