Employee Leave Policy: Personal Needs vs. Company Rules
Generally, we must not allow any employee to take leave for personal reasons, regardless of the justification they present. The employer is not concerned with the employee's personal needs or requirements. Employees must manage their personal matters, such as studies or other personal work, on their own. They are already aware of the company's rules, culture, and atmosphere, and upon joining the organization, they agreed to the terms of employment, which they must follow. Every employee in the organization is required to adhere to the policies laid down and maintain them under all conditions. It is also the duty of HR and Admin personnel to uphold the company's atmosphere and ensure no one disobeys the rules. If one employee is allowed to take leave for personal work (including study leave), others will certainly request the same, which the employer cannot accommodate at any cost.
These days, many employees are pursuing studies and need time for it. However, this does not mean they can disobey employment rules or request leave for personal reasons, as it is a personal problem and not a concern for the employer.
Compensatory Work Arrangement
I agree with Rajeshwari. The employee can work extra hours to compensate for Saturday's leave, but this requires prior consent from you and his supervisor or boss. Ultimately, it depends on you, your boss, and your company policy whether to allow him or not.
Decision-Making in the Absence of HR Setup
You mentioned you are new and there is no proper HR setup in your organization. In that case, you need to discuss this with your and his department supervisor and boss. If the bosses agree, you can allow the employee to take a half-day leave, but only when it is absolutely necessary. However, do not make any decisions without the proper consent of the Heads of Department (HODs).
In closing, I would say NO, you should not allow him to take leave for this.