This is another verse that seems to be the response to a question rather than a statement.  The vocabulary is like Matthew 5:18, but the form of "tittle" is non-standard. 

The Greek word translated as "but" means "but", "however", and "on the other hand". Since it always falls in the second position, translating it as "however" often captures its feeling better. 

The verb "it is" here is the common form of "to be" in Greek. It means to have a certain characteristic or remain in a certain condition. It also equates terms or assigns characteristics. -- When the verb "to be" appears early in the sentence before the subject, the sense is more like "it is" or, in the plural, "there are." 

The word translated as "easier" is a compound of two words. It is an uncommon word, appearing only a half dozen times in the NT and only five times in the rest of ancient Greek literature. The prefix here means "good" or "better" because the word is comparative. The base word primarily means "beating" or "fatigue". So the sense is "better fatigue", which has the sense of "less tiring".

There is no "for" here. It is added because the "heaven and earth" are in the form of an object, but there is no verb that takes and object, so the proposition is added. However, in Greek, an objective noun without a verb is more like adding the English verb "have" to the verb. 

The word translated as "heaven" means "sky", the "climate", and the "universe". It also meant the home of the gods in a physical sense: the sun, moon, and planets were named for the gods. More about the word in this article. It is introduced by an article. "the sky". 

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

The word translated as "earth" means "ground" and "dirt". Translated as "earth", it refers to the physical planet, not society, which Christ describes as the world. See this article for more on these words.

The phrase "to pass " is a verb that means "go by", "pass by", "outstrip" (in speed), and "pass over".  The sense here could be "pass by", "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 means "to cross". In Greek, the form is neither active nor passive, but the middle form which means that the subjects are acting on themselves.   It is in the form of an infinitive, "to pass". 

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

The Greek word translated as "one" means "one" (as opposed to other numbers), "single," and "one and the same."

"Tittle" is from the Greek form of the apostrophe. The word "one" precedes this word.  However, this form is not a standard Greek form. 

The Greek word translated as "of the law" describes the social norms, which can be from "tradition", "common practice," or the "laws." Christ also uses it to refer to the first five books of the OT written by Moses.

"To fail" is translated from a Greek verb that means "to fall" and "to fall down." It is the root word for dozens of Greek terms involving moving from a higher state to a lower one. Like our word "to fall" it has a number of special meanings including "to fall into a given class", "to prostrate", "to fall from power", "to perish," and so on.