A redemption is the process of exchanging LUSD for ETH at face value, as if 1 LUSD is exactly worth $1. That is, for x LUSD you get x Dollars worth of ETH in return.

Users can redeem their LUSD for ETH at any time without limitations. However, a redemption fee might be charged on the redeemed amount.

They represent a separate mechanism of securing the LUSD peg.