The post permission settings of Friendica showing 2 input boxes. In the first box you can choose who can see your post, the example in the screenshot has the Followers group tagged. In the second box you can choose exceptions to who can see the post, the example in the screenshot has the Mutuals group tagged.
https://cdn.fosstodon.org/media_attachments/files/108/906/077/191/989/244/original/b70dda22a0986fc0.png