Another kind of bet is the number of 180s in a match, which is a straight-forward bet on how many maximums you think will be thrown. Sometimes there is an over/under market for this bet, which would read something like: +4.5 180s in the match.
The term bet can be used in a few different ways, but generally means "agreed" or "okay". For example, if someone says "Wanna grab lunch later?" and the other person responds "Bet", it means they agree to the plan. Bet" can also be used as a response to confirm that a statement is true.