TimeSite Pro can be used to record leave details such as annual leave, sick leave, rostered days off, and so on. These timesheet records can then be exported to your payroll system along with other timesheet records for the calculation of leave loadings, and updating leave balances.
Our general recommendation is to create a Client record using your own company name or something like "Internal" or "HR". Then create a Project and call it something like "HR" or "Leave" or "Admin". Then create individual Tasks for the different leave and other timesheet entries that don't relate to a specific client or project. For example, you might include non-time tasks for expenses, travel, accommodation costs, and so on.
So you could have a Client > Project > Task hierarchy such as:
>>> Annual Leave
>>> Sick Leave
>>> Compassionate Leave
>>> Staff Meeting
>>> Parking Expense
>>> Travel Expense
You can then map these tasks to your leave and expense payroll categories in Settings > Export Timesheets > Payroll Mapping > Task Type -> Payroll Category. See Payroll Mapping to Task Types for more information on mapping.