You may already be doing this and if you’re not you should be.
What does replate mean?
It’s to place unwanted leftovers, typically in a doggie bag, on top of the nearest trash can so that they don’t go to waste. That way someone who’s hungry enough to pick up your leftovers will get something tasty, rather than having to shuffle through the can to find some scraps.
It’s simple enough that everyone can do this, and common enough that everyone should.