In cases where a point spread falls exactly on the number you bet, that wager will be considered a "push" and will result in "No Action" (the bet is canceled and the money returned to your balance).
For example, you take the Kansas City Chiefs -4 and they win the game by a score of 24-20. This is a push and any bets placed on the favorite at -4 or the underdog at +4 will all have no action.
Pushes can occur on total (over/under) bets as well.
However, with moneyline betting, a push will only happen if the game/match ends in a tie. Exceptions apply to sports where a 3-way line offers the draw as an option.