Short answer: a lot 😉 its an authentication protocol to have a single identity provider take care of all your users passwords, access rights etc., like those “login with Facebook” buttons.
It’s a bit of advanced topic, but a solid way to minimise authentic based alley on username and password.
I spun up version 0.3 to try it out, and it seems pretty and lean in comparison to paperless. However, it lacks a lot of functionality - I couldn’t even change the name of the document.
I get it, its a very new project and I imagine it will kick ass once it matures, however it is too bare bones for me right now.