Basically people can run relays to facilitate the network and Nostr clients subscribe to them and send messages which get published by the relays.

Supposedly these relays don't speak to each other. You make an account through a client which gives you a public key and a private key (sort of like a username and password) and these keys are used to sign all your posts and interactions so clients can validate the ID of whoever is posting it

Its "censorship resistant" because relays can boot you from using them but you can just start using another relay and tell your followers to use it too so they can still interact with you but I don't really think it works that well in practice because the majority of the network flows through a couple of main relays so getting kicked off of those means you are cut off from a lot of the network.

IMO it's more centralized than fedi despite its claims of being decentralized