At the level of the "Roles" section Schema Editor role is nothing more than just a name. Name is the only parameter set when a new role is created. All the logic behind the roles needs to be implemented in appropriate schema section. The below list presents all the schema parts, where roles can be used:
You can add as many roles as you need. A single user may have any set of roles. The set can even be empty, when a user has no role assigned. This is what happens when a new instance/database is created and roles are not yet defined.