The wagering requirement (also called playthrough or rollover) is the most critical part of any bonus. Mechanically, it is a multiplier that determines how much total volume you must bet before bonus funds and their winnings "convert" into real cash.
Operators use these requirements to prevent "bonus abuse," where a player might claim a bonus and immediately withdraw it. By requiring a certain amount of gameplay, the platform ensures the bonus is used for its intended purpose: entertainment.
There are two main types of requirements: Bonus-Only (where only the bonus amount is multiplied) and Deposit + Bonus (where both your deposit and the bonus are multiplied). The latter creates a much higher total wagering target. You can find the exact multiplier and the total amount remaining to be bet in the "Promotions" section of your account.