For example, in a first goalscorer bet with bet365, if the player you backed doesn't play, they will void your bet. But instead of refunding your bet in cash, they will refund you in bets. If you bet on horse racing at bet365 and your horse is not a runner, your bet will be void and your money will be refunded.
There are several reasons why bet365 accounts can be restricted, including matched betting, unreasonable betting behaviour, GamStop (self-exclusion), and exploitation of bonuses.