Originally Posted by selena

Assuming you are seriously asking...

"Take Denver at -3.5 over St Louis"

Means that in order for him to win his wager, Denver must beat St. Lous by more than 3.5 points. If Denver wins by 3, he won't cover.

"San Fran vs Arizona you can take the over at 42.5"

Means that you can bet that the combined score of that game will be higher than 42.5 points.