In My Hours you can easily track absences. To enable this, create a new project and title it ‘Absence’. Add all types of absences (sick leave, annual leave, maternity leave,…) as tasks to that project.
Then your team members can simply put in hours for the ‘Absence’ project (with the correct task/type of absence) when they are missing from work.
You will be able to view all absences in the Activity report, which you can filter for the ‘Absence’ project and a specific team member in a selected time period.