Upaya is a fancy word that means using clever tricks or methods to solve a difficult problem. Imagine you have a jar of pickles but it's really hard to open because the lid is stuck. You could try using your hands to twist it open, but that might not work. So instead, you might try banging the jar lightly on the counter to loosen the lid or running it under warm water to expand the metal. These are different upayas to solve the problem of opening the jar.
Upayas aren't just for pickles, though - you can use them for all kinds of things, like schoolwork or relationships. Let's say you're having trouble with a math problem. You could keep trying the same method over and over, but if that's not working, you might try thinking about the problem in a different way, using pictures, or asking someone for help. These are all different upayas that could help you solve the problem.
So remember, upaya is just a fancy word for using your smarts and trying different tricks to solve a tough problem!