As a manager you can approve or decline a request for time-off  in QBIS under  Time-Time-Off Planner and the tab Requests. Here you can see all the applications that have come in to you.

In order to process an application, click on the row which then opens up.  To approve or decline the application, simply click the appropriate button.

Go to the overview page to see a great overview of all planned time-off.