A Wagering Requirement (WR) is a figure that represents the number of times a player has to “play through” the bonus before being eligible to cash out winnings. Wagering requirements can vary based on the generosity of the bonus. At Oshi they’re normally around 40x, but can change for different bonuses.
For example, suppose a player deposits 20 EUR and gets 10 EUR more in bonus money for a total of 30 EUR. If the WR is set at 40x, the player will have to make 10 x 40 = 400 EUR worth of bets to cash out the winnings. Until then, the full amount of money will be locked due to the active bonus. Note that the player can cancel their bonus at any time. Note also that some games contribute less to the wagering requirement; details here.
Bonus wagering requirements are set up when creating bonuses.