In this problem, we're asked to find the perimeter of a square that is 5 cm on a side. Remember that a square has 4 congruent sides so if one of the sides has a length of 5 cm, then all four sides of the square must have a length of 5 cm.
So to find the perimeter of the square, we simply add thee lengths of the four sides. 5cm + 5cm + 5cm + 5cm = 25 cm².