Think of cashu as an intranet on top of Lightning. Instead of using channels or routing, it implements chaumian mints and tokens to improve privacy. While tokens are pegged to sats and can be used as ecash, the mints are run by trusted community members, like friends or family. Meaning that, mints reduce the need for intermediaries, like exchanges or banks, but simultaneously increase scalability and privacy because minting ecash breaks links to past transactions due to using blind signatures. Sorry that’s one hell of a word salad, hope it made sense to you… I am also in the process of wrapping my head around it, but it’s very exciting stuff. Here’s a way better explanation by @calle https://m.youtube.com/watch?v=UNjVc-WYdgE