A bet can show as pending for one of two reasons:
It is still waiting to be accepted. Live bets may take a few seconds to be accepted, and during dangerous moments in a game, such as a free kick or a 1-on-1 attack, your bet may stay pending until the situation is over.
It has been accepted and is waiting to be settled. Bets are settled after the event has ended and the official result has been confirmed, so your bet stays open until then.
In some cases, the official result is confirmed later than usual, which means settlement can take a little longer.
You can check the status of all your bets at any time in “My Bets”.