Original: In cryptography, a permutation box (or P-box) is a method of bit-shuffling used to permute or transpose bits across S-boxes inputs, retaining diffusion while transposing.
Simplified: In cryptography, a permutation box (or P-box) is a method of bit-shuffling used to permute or transpose bits (rearrange or swap the order of bits) across S-boxes inputs, maintaining diffusion while transposing.