Two or more terms in an algebraic expression are like terms if they have the same variable(s) with the same exponent(s). In this expression, there are three sets of like terms — namely, $xy\text{-}$terms, $x\text{-}$terms, and $x^2\text{-}$terms.

Note that all constants are like terms. Like terms in an expression can be combined by using addition or subtraction to rewrite the expression in simplest form.