In the above example, the number is 217.5, meaning you would win an over bet if the score exceeded 217 total points but lose if the total was 217 points or fewer. Over/Under bets are fun ways to have a stake in a game's outcome without having to worry about which team will win.
In sports betting Over 237.5 Points is an example of a total market you might see when betting on Basketball. When betting on the Over market you need the total points of a game to exceed 237.5 for your bet to win.