"Total Over" or the "TO" bet here means a bet wagered on the quantitative outcome of a certain event exceeding the selected result. Let's take the number of goals in a football match and the total bet of "TO 2.5". This outcome implies that 3 or more goals are to be scored in the match.
A wager on the Total or the Over/Under of a game is a wager on the number of points, runs, or goals in a game. The sportsbook will set a line, and the bet will be on whether the game total will be Over or Under the line. Totals are available on a wide range of team or player statistics.