I mean any kind of minority, although I would generally say "marginalized group" instead of "minority." But this is HN, so trying to stick to more commonly-known terminology :P
I also think the "latinx" thing is overblown and generally used as an "anti-woke" shibboleth by people who want to get mad at something. Literally never seen an Anglophone yelling at a Spanish speaker about it before, only queer Spanish speakers who use it to refer to themselves.
Also worth noting that there have been other variations that predate "latinx" and have seen more widespread usage. There's "latine," and "latin@", although the former is both easier to write and to pronounce.