In an over-under bet, a sportsbook will predict a number for a given game. Most commonly, this is the total number of points that will be scored. Bettors will then wager that the actual number will be higher or lower than this prediction. With this type of bet, you are not trying to predict the actual score of a match.
Goal line under 3. - Bets win if there are 0, 1 or 2 goals scored in the match. If there are three goals exactly then the stake is returned. Bets lose if there are four or more goals scored in the match.