I'll explain by using an example first.
Let's say that you are given the area of a square is 64 square meters. You find the area of a square by multiplying the base and height or just side². Therefore, you find the length of one side by square rooting the 64, which equals 8. Because you know there are 4 congruent sides in a square, the perimeter is 4×8 = 32 meters.
Step 1: take the square root of the given area to find length of one side
Step 2: multiply the square root by 4 to get perimeter