Here is a sample email that you can send to your manager, boss, or principal to request approval for one day or several days off.
Subject: Vacation request (August 2nd through August 10th)
I want to request vacation time from Friday, August 2nd, through Thursday, August 10th. I'll be traveling with my family around Italy.
Although I will not be in the office, I would be glad to assist with any questions via email or phone. If approved, I will arrange with my colleagues' smooth work during my absence.