If you have received a leave application from an employee, here is a sample template you can use to write an acknowledgment letter for leave.
This letter is regarding your leave request from [From date]- [To date] for the [reason]. I can understand the gravity of the situation and your genuine requirement for the leave. Your reason is valid and I hereby confirm that I have acknowledged your request.
I will check in with concerned officials and will keep you informed about the status of your leave sanction. Arranging a substitution for your engagements to avoid disorienting the workflow can take a little time.
I will do the best in my power to grant you the leave. However, until further notice, your patience is requested.