The pay element that is Subject to GRP means it contributes to the Gross Salary. If the employee's basic salary for the month is $2,000 and the pay element (subject to GRP) is $1,000, then the gross salary is $3,000.
In this month's payout, if you have another pay element with a GRP Code, such as Annual Leave Pay, the system automatically generates the Annual Leave Pay as $3,000.