How to grant right for attendance to the teacher?
Administrator can grant rights to modules on the EduPage: User rights - Overview
Any teacher can enter attendance of students in Class register, class teacher can excuse or not excuse absence: Teacher - Attendance
There is no need to assign any right to attendance to the teacher, he or she has it automatically in his class.
However, if you need another teacher (not a class teacher) to excuse absences, you need to give him/her a right.
To add the right to the teacher check the box in the column Attendance(students) - Administration and save the changes.