A 0.5 Asian Handicap is a popular betting market in sports betting. It is also known as a half-goal handicap. A 0.5 Asian Handicap means that one team starts the match with a half-goal advantage over the other team. In a 0.5 Asian Handicap, it depends if you placed a bet on the favourite (-0.5) or the underdog (+0.5).
The sign of 1.5 in the handicap bet itself indicates the math to be done: a Handicap (-1.5) means that we subtract 1.5 from the number of total goals scored by the team, while a Handicap (+1.5) means that we add 1.5.