Raise to the power:

(-0.2xy) 4

Since there are parenthesis, you have to distribute the exponent to the whole thing. That ends up as - 0.2^4 x^4 y^4. - 0.2^4 can be simplified, it’s - 0.0016. End answer is

-0.0016 x^4 y^4. The ^ symbols just mean that it’s to the power of four. x^4 = x to the power of four.