Are you a developer? If not then the only thing you need to know is that Mozilla is essentially announcing enabling desktop extensions to be able to work on mobile
I've used Firefox Nightly for ages, and admittedly, it sometimes lets a crashing bug through. But it was worth it for stuff like old.reddit redirect on tablet, lol. I just don't want the stupid "USE OUR APP" banners while searching.
It's an extension that allows you to blacklist certain websites from appearing in search results. So if you wanna prevent for instance facebook links from showing up in search results, uBlacklist can make that possible.
Firefox Mobile supported add-ons for many years, but due to having to change some things under the hood a few years ago, add-ons got restricted a bit (though you could still use them).
They're basically announcing they finally fixed the issue and they're coming back.
They don't spell this out, but my interpretation is that extension devs will be able to publish extensions for use on Android, without Mozilla explicitly approving each one of them.
Many desktop extensions work as-is on Android, so when this goes live, we'll likely see dozens, if not hundreds, of extensions becoming available in the following weeks.