Jesus is talking to a group of people about what might happen to them as individuals. The instances of "you" and "your" are plural, except in verse 21, where they are singular. (See: [[rc://en/ta/man/translate/figs-you]])
# treasures
"riches"
# where moth and rust destroy
"where moth and rust ruin treasures"
# moth
a small, flying insect that destroys cloth
# rust
a brown substance that forms on metals
# store up for yourselves treasures in heaven
This is a metaphor that means do good things on earth so God will reward you in heaven. (See: [[rc://en/ta/man/translate/figs-metaphor]])