The line -10 means a team is favored to by 10 points. When a team has a – sign after it, that team is the favorite and the number following the – sign is how many points they are favored by. If you see Dallas Cowboys -10 vs. Arizona Cardinals, that means the Dallas Cowboys are a 10-point favorite against the Arizona Cardinals. For a bettor to win a bet on the Dallas Cowboys they must win by more than 10 points. If a team has a + sign after it, then that team is he underdog and the number following the + is how many points they are “getting’’. In this same example the Arizona Cardinals would be +10. In that case any bettor who places a wager on the Arizona Cardinals needs the team to either the win game or lose by less than 10 points to collect on his, or her, bet.