Yeah watch the vid @RawBTC shared, it’s a good one. The super nutshell version is it’s a way to host a custodial service and verify transactions for your users, except you have no idea how much ecash is moving around or where it is going. It’s all blinded. All they can tell is if it’s “real” ecash, and they can sign it.

Even shorter, it’s a tool to create a totally private service where even the operator doesn’t know what’s going on.