In essence: Digital Standard Unit is a wrapper for stablecoins. The protocol consumes a particular collateral, places it into a reserve and issues a stablecoin, known as DSU, against it. The act of wrapping has a number of benefits, ranging from trust-minimization to risk reduction for upstream protocols.
Users are able to mint DSU by providing the specified collateral, currently this is USDC. They are also able to redeem USDC from DSU at a 1-to-1 ratio with DSU. This allows for perfect arbitrage between the collateral and DSU, which in-turn keeps the peg tight.
Empty Set is designed to reduce upstream distruption for protocols implementing DSU as collateral. If a stablecoin is forced to wind down or new risks related to its backing may emerged, protocols directly utilizing this asset will need to fork away from it. Instead protocols utilizing DSU can continue undisrupted while DSU manages the migration to a new collateral for all upstream protocols.
By holding or integrating DSU you are taking on a different set of trust assumptions than if you were interacting with the underlying collateral. This minimizes the trust required between the collateral issuer and you while maintaining the redeemability of the underlying asset. With DSU you are engaging with a decentralized protocol and governance instead.