Edge Parity on a 5x5 occurs when you pair the last edges and one edge doesn't match. This is because the two "wings" need to be swapped.
Perform this algorithm with the flipped edge piece in the front top position.
Rw U2 x Rw U2 Rw U2 Rw' U2 Lw U2 3Rw' U2 Rw U2 Rw' U2 Rw'
The solution above can be used for 4x4 up to 7x7. The video below explains.
