If you enable this option which means your employees won’t be able to enter the time manually as below.

To enable this option, you need to log into your admin account.
- Go to the System Module and click on Settings
- Then go to the Attendance module
- You will be able to find Attendance: Use department time Zone section
- Click on the Edit button to make changes
- Set the Value Yes and Save

When you enable this option, as you can see in the above screenshot employees won’t be able to enter time manually.