Fediverse is the name of a decentralized protocol in which different servers federate with one another, a bit like email. Mastodon is decentralized Twitter, Lemmy is decentralized Reddit, and there are a lot of others.
Sorry, should've been more clear. My question wasn't about what the name meant, it was about them using the word fediverse but the site only shows American news, when the fediverse (being a global decentralised network, and used quite a lot in the non USA part of the world) has more than American news.