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 theorem is typically expressed mathematically as \( a^2 + b^2 = c^2 \), where \( c \) is the length of the hypotenuse and \( a \) and \( b \) are the lengths of the other two legs.