The User Roles feature allows you to create roles, assign them to members or member groups, and then filter content based on the roles assigned to that member or the member groups they are in. It's a great way to restrict blocks of content, forms, admin tools, viewing of channel entries, etc to users with sufficient privileges on the front end EE templates.
In the main page of the Roles control panel area, you can create roles and give them descriptions.
In the Assign Roles control panel area, you can assign roles to members or whole member groups.
When roles are assigned to a user, you can use them with User Roles template tags to filter content based on who has the role. For instance, with the User:Has_Role tag, you can restrict blocks of content, forms, admin tools, etc to users with sufficient privileges. With the User:Roles_Entries tag, you can restrict users from seeing entries only that have matching combinations of roles assigned to them.