Welcome to the Community, Venoth. You can add a vacation policy by going to the Time off section in each employee's profile.

Once you've created the policy, go to the Time off section again and select Make adjustments to edit Vacation hours and Vacation balance.

To show the balance on pay stubs, go to Payroll Settings, then click the pencil icon in the Printing section. Then, enable Show accrued vacation balance on pay stub, then click Save and Done.

To learn more about vacation in Payroll, please check out these articles:
If you have any other questions, don't hesitate to leave a comment in the thread.