Basically, Lemmy communities and Kbin magazines are federated as groups to the micro and macroblogging fediverse. People in friendica, mastodon or Firefish can interact with Lemmy and kbin by mentioning a community/magazine in their posts and following them the way they do with other types of federated groups (like guppe, chirp, friendica forums, etc)

Pixelfed didn’t have federates group support, meaning that its federation with the threadiverse was bad, not to say practically non-existent. Supporting federated groups and even having its own type of group will allow people on pixelfed to interact with Lemmy and Kbin the way other fediverse software do: following them and tagging the community/magazine handle in posts.

short summary: It means better federation between Pixelfed, and Lemmy and Kbin.

Pixelfed is basically a federated alternative to Instagram that’s been picking up a massive amount of momentum. The Groups feature is more or less federated Facebook Groups, with a bunch of robust tools built in, and will be compatible with Lemmy communities and Kbin magazines.

The reason this is significant is that it may prove to be the final push that makes groups a standard part of the Fediverse experience. Some of the biggest platforms in the space have lacked it, for years and years. This implementation could prove to be a really good blueprint of what the standard experience ought to provide, at a bare minimum.

The biggest, most significant reveal at this stage of development is that Pixelfed’s groups feature will be launching with compatibility for both Lemmy and Kbin, officially connecting Pixelfed to the rest of the “threadiverse” that the other two platforms occupy.

From my understanding, we’ll be able to see Pixelfed groups on Lemmy just like any other community and follow them. There could be a group/community, where people publish photos of cats, their art, urban photography, etc.