Hi! I've noticed that before the Notifications, Replies and Bookmarks menu items are populated with stuff, there's actually a very good explanation of what you'll find there. When I first started using Discourse as an end user, those explanations were already gone when I started exploring the menus, and it would've helped me to have those explanations available then, too.
I suggest that if you tap/click (in my case, tap - I almost always work on my iPhone) on the Bell icon, Left Turn icon, etc a second time, the explanation of its use pops up in a text box.
Discuss this on our forum.