The correct statement that explains the Pythagorean Theorem is:
If a triangle is a right triangle, then the sum of the squares of the legs is equal to the square of the hypotenuse.
This statement accurately describes the Pythagorean Theorem: \( a^2 + b^2 = c^2 \), where \( a \) and \( b \) are the lengths of the legs, and \( c \) is the length of the hypotenuse.