Some companies offer loans to employees against their future earnings. Normally Generally, these kind of loans will not carry any interest.
The tenure, number of installments, etc. would be as per the terms of the company. Normally this Typically, the installment amount would be is deducted from subsequent monthly salaries of the employee. However, if the employee resigns before completing the loan repayment, as part of dues clearance, the company may request employee to settle immediately or adjust in Full & Final Settlement as part of dues clearance.