I. option: From the Admin calendar
Once you selected “Holiday”, you can fill out the information in the event editor.
Give it a title.
Add a start date.
Click on Repeat button.
Set the repeat frequency.
At the Repeat until field, set your holidays end date.
Once you’re done editing, click on the “Save” button in the bottom right corner.
I. option: Date override from Working hours.
Suitable if you are away for 1-2 days.
Go to your Admin page.
Go to Settings > Working hours
Click on the "Add date override" button.
At the Working day menu, choose No.
Click on the "Add" button.
Save your Working hours when you're done editing.