When you invite a new employee you can choose not only the role but also the courses the instructor is going to be responsible for. You can change the role and the rights any time with the "Edit access" button on the employee card.
Users - Employees - Edit access
Click "Instructor" role:
* If you want the instructor to have access to all courses (including the ones that will be created later), click on "All school courses" checkbox.
* If you want the instructor to have access only to certain courses, click on checkboxes needed.
Instructor will see only available courses on the main school page. Instructor will see the reports on completed assignments and will get notifications in the "Assignment under review" tab only from the courses he has been assigned to.