If your employees work on a public holiday, by default, you as the employer should pay him/her an additional day's pay.
Your employee's monthly gross salary already includes payment for the holiday, so you only need to pay him/her an additional day’s pay
If your employee is absent without reason on the working day before or after the holiday, he/she is not entitled to the holiday pay. You can therefore deduct one day’s pay (or no pay leave) at the gross rate from your monthly gross salary.
In Talenox, you can process Public Holiday Pay under the Hourly/Daily Attendance tab:
Thereafter, key in the total number of days and the figures will be auto-calculated under Amount field.
Alternatively, by mutual agreement, your employee can get a public holiday in lieu instead. (Here's an article to guide you how to set it up in Talenox) 😎