You can attach metadata to nostr accounts (or public keys). This means you are able to set an "alias" to your public key (a name, not a unique username), some description (like a bio) and a profile picture (by linking an image).
Most clients will allow you to set such metadata, but you can also use this tool to do it!
There is a way to "verify" a Nostr account. The NIP-05 specifies a verification method for accounts via domain names.