In practice, if Team A is playing against Team B, and Team A is favored with a runline of -1.5, they need to win the game by a score of 5-3 (for instance) for a bet on them to pay off. If Team B loses 5-4, bets on Team B would win, while bets on Team A would lose since they didn’t cover the spread.
Runline Example
For example, if a game ends with Team A beating Team B 6-3, bets on Team A would win if placed on the -1.5 runline, while bets on Team B would win if placed on the +1.5 runline.