This kind of betting was first introduced in Indonesia back in the late 90s and picked up really well in the early 21st century. What happens in this kind of wager is that one side of the two playing football teams is awarded some goals prior to the kickoff of that match. So, one of the teams will look like it is trailing or ahead of the other by some goals depending on which side has been awarded the goals.
Most often or not, the team that is awarded some goals is deemed to be the weaker of the two. The odds for the two will also change depending on the number of goals handicapped to one of the teams. The more the number of goals awarded, the lower the odds it gets for the advantaged teams while the odds for the disadvantaged increase tremendously.
I do prefer doing an illustration in tabular form so as to be clearly understood. Allow me to use a random football match between FC Copenhagen (Denmark) and FC Twente (Holland).
FC Copenhagen = (10.1)
X = 8.56
FC Twente = (1.14)
FC Copenhagen = (6.4)
X = 4.22
FC Twente = (1.35)
FC Copenhagen = (2.11)
X = 3.72
FC Twente = (1.89)
This way of displaying Asian handicap is found in Unibet bookmaker. The other bookmakers have different ways of doing that but the odds rarely change.
As you can see, the weaker team (FC Twente) has been awarded goals but its odds are lower compared to those of FC Copenhagen. The goals to be awarded go both ways. What I mean by this is that either home team or away team can be awarded the goals depending on their strength. Do not be surprised to find this wager having awarded home team or away team goals. These situations do happen especially when both teams are believed to be of equal abilities to win the match.