U 52 translates to under 52. Meaning the total points of the game being bet must be less than 52 points for a bettor who takes this bet to win his wager. An example would be if the Dallas Cowboys and Washington Redskins are playing and the bettor takes under 52 as the bet. The score must stay under 52. If the Cowboys win, 28-21, (total 49), the bettor wins. If the Cowboys win, 28-27, (total 55) the bettor loses the bet. If the Cowboys win, 28-24 (total 52) the bet is a push and the bettor breaks even. It doesn’t matter if the game goes overtime (unlike European football) if the total exceeds 52 the bet is a losing bet.