An over/under bet in the NBA refers to wagering on whether the combined score of both teams in a game will be higher or lower than a specified number set by the sportsbook. To place this bet, simply choose either "over" or "under" the total and hope the final score matches your prediction. Over/under bets are a popular option for NBA fans as they don't require predicting the winner of the game, but instead, focus on the offensive and defensive capabilities of both teams.