# truly I say to you

"I tell you the truth." This phrase adds emphasis to what Jesus says next.

# until heaven and earth pass away

The phrase "heaven and earth" refers to the entire universe. Alternate translation: "as long as the universe lasts" 

# not the smallest letter or the smallest ... will in any way pass away"

"even the smallest letter and the smallest ... will not in any way disappear"

# until all things have been accomplished

"until all things have happened" or "until God causes all things to happen"

# all things

The phrase "all things" refers to everything in the law. Alternate translation: "everything in the law" or "all that is written in the law"