On the Class List tab, type your school, class and each learner's name once. On the Attendance tab, pick the month and mark each day P (present), A (absent) or L (late) from the dropdown in every cell. The Present, Absent, Late and Present percentage columns update on their own, so a full month of marks becomes a set of numbers you can act on.
The Monthly Summary counts enrolment, present and absent marks, average attendance and the overall rate for the class, while the Absentee Report lists every learner against a threshold you set (90 percent by default) and flags anyone below it as REVIEW in red. Yellow cells are the only ones you type in; every other cell is a locked formula. It opens in Excel, WPS or Google Sheets on a phone, with no macros.