What does +4.5 mean in sports betting?

In sports betting, a "+4.5" indicates the point spread for a particular team in a game. When a team is listed with a +4.5, it means they are the underdogs and are getting four and a half points added to their final score for the purpose of the bet. This means that if you bet on that team, they can either win the game outright or lose by fewer than four and a half points for you to win the bet.

For example, if Team A is playing against Team B and Team A is listed as +4.5, if you bet on Team A, they can lose the game by four points or fewer, or win the game outright, for your bet to be successful. If Team A loses by exactly four points, the bet is a push, and you get your wager back.