The Banker Bet is a special option available in system betting. When you place a system bet, a "B" appears next to each selection, indicating the choice to activate the Banker function.
If you're very confident that one of your predictions will likely win, you can mark it as the "Banker" by clicking the "B" next to it. This will make the system treat that prediction as a sure win, combining it with your other bets.
If the Banker wins: Your bet's overall odds increase, which can lead to bigger winnings.
If the Banker loses: The entire bet loses — even if all your other picks were correct.