Solutions :-

You can fill the Leave application From the HR module and from the Employee section.

Click on Transaction > Click on leave > click on application add > fill the leave application information which is required > click on save.

The same process from the employee section if you want to fill leave from the employee section

This application HR will approve from the list of leave applications.

Fill the information as per need. And click on save

Click on list > click on search > you can edit the Application also you can approve the same.