Assume an employee is managed by two managers. When he/she lodges a leave request, sometimes each of the managers needs to approve the leave request individually before it is finally approved.
To ensure both managers of the employee approves the leave request, the company can choose to use two level leave approval.
These settings can only be actioned by owners or admins.
To turn on two level leave approval, go to:
Settings > Company Settings > Two Level Leave Approval > tick "Two level leave approval"
It is now in effect and you can manage leave in the Leave module.