So I understand this instance is integrated with XMPP and also vaguely understand XMPP is a chat protocol? It would be great if someone could point me towards a simple explanation around anything else important, I’m a bit lost and the only ‘chat thingy’ I use are messenger apps (is that even the same?)
You can compare it with e-mail … in a way.
You can set up a server, you can register on an existing server, and you can communicate with everyone else, regardless what server they use. You can send long text, you can send short text, or media. But not as asynchronous mails but as chat messages like in any other common messenger service.
Like with e-mail you’re not limited to a specific app or a specific website or software. You don’t need to give someone your phone number, or do weird authentication things. You can have REAL end-to-end encryption, too. Most clients support that.