Under the menu ☰ you will find the settings page. This page has a Roles tab where you can add new or edit existing roles.
Lytho users can be given different roles depending on what they should, or should not be able to do. For each role a set of rules can be selected or left unselected. For instance, rules can give a user access to a module, rights to add/edit/delete assets or rights to manage settings.
Administrators can easily define many different roles, each with it's own set of rules.