The wagering requirement (also called playthrough or rollover) is the most critical part of any bonus. Mechanically, it is a multiplier that tells you how many times you must bet the bonus amount before it becomes withdrawable cash. Operators use this requirement to prevent players from claiming a bonus and immediately withdrawing it without actually playing.
There are two main types of wagering: Bonus-Only (where only the bonus amount is multiplied) and Bonus + Deposit (where both the gifted credit and your initial deposit are multiplied). The latter effectively increases the total amount you need to bet before the funds are unlocked.
Your progress is tracked automatically by the system. You can usually see a progress bar or a remaining amount in your account profile. To find the specific multiplier for any current offer, check the "Terms and Conditions" link attached to that specific promotion in the 777pinas promotions area.