What does Matthew 22:32 mean?

Jesus has corrected the wrong assumptions built into a question put to Him by a group of Sadducees. Now He turns things around: using their own strategy against them. Their question attempted to use Scripture to prove something to be absurd, though the attempt failed. Christ is now showing a valid example, where Scripture proves that there is life after death. Since the Sadducees only accept the Pentateuch—the first five books of the Old Testament—Jesus makes the case for resurrection from the book of Exodus.

God spoke the words of Exodus 3:6 to Moses from a burning bush. Moses lived centuries after Abraham, Isaac, and Jacob had died. And yet, as Jesus notes, God would not have described Himself as Jacob's God if Jacob had ceased to exist. He did not say "I was the God of Jacob," but claimed "I am the God of…" those patriarchs. Jesus insists that God is the God of the living and not the dead. This means Abraham, Isaac, and Jacob all still existed, in an afterlife.

Matthew records in verse 34 that Jesus silences the Sadducees with this. They had no response to His correction.