You just multiply the exponent inside the parentheses by the on outside and you would get 5 to the power of 6 which is equal to 5to the power of 2 times three which equals 5 squared three times.
In powers, when there are 2 powers, one outside of parentheses and one in, you add to combine powers, not multiply them. So what this problem is saying is (5^2)^3, or 5^5, which equals 3125.