What do the various symbols mean on my activity feed?

At mention button

@mentions of you specifically.

Teams button

@team mentions for teams you're on.

Channel mention button

@channel mentions in teams you're on.

Reply button

Replies to your posts.

Like button

Posts you liked.

Add people to team button

You were added to a team.

Team owner button

You were made a team owner.

Trending button

Trending posts.

Suggested Feed Item Button

Suggested posts.