A point-spread makes each team equal in the eyes of the betting public.
In a point-spread bet, the favorite in the game has to win by more than a certain number of points for the bettor to win if they bet on the favorite.
In a point-spread bet, the underdog in the game either has to win the game or cannot lose by more than a certain number of points for the bettor to win.
What this means is that, if you bet on Los Angeles, they have to win the game by more than 6 points for you to win your bet. This is in betting terms is “giving the points.”
If you bet on San Francisco and they win the game or lose by less than 6 points, you win. This in betting terms is “getting the points.”
Hypothetically, Los Angeles wins the game 21-17. If you bet on Los Angeles, you lost because you “gave” 6 points and they only won by 4. On the other side of the coin, if you bet on San Francisco, you won. This is because even though they lost the game you were “getting” 6 points and they only lost by 4.
As a note, if the game had ended at 23-17, it would have been a tie, or a “push” as they call it in betting, and all bets would be refunded.