What settings can I change in the user management?

The User Management tile is only visible in the main menu with system administrator status. 

The user management allows you to manually create, customize and manage users and their authorizations. The following article explains this in more detail:

How can I create, edit or delete users?

In the admin dashboard these created users can be added to or removed from groups. In the section "Users" you can also filter users individually via a search field.