This is used primary in betting on European football, or soccer. All American football basically uses the Asian Handicap, it’s just not called that.
Asian Handicap is a type of wagering that effectively gives the underdog an advantage. Again used in soccer, Asian Handicap removes the “draw” option for bettors and provides an edge to the underdog.
In typical soccer betting, you need to select either team to win the game outright on the money line or the draw (1×2 betting). That gives you three options. Asian Handicap gives the bettor a line or a goal-spread in which to wager. The favorite must win the game by whatever number the Asian Handicap indicates for the bettor to cash a bet on the favorite. The underdog doesn’t necessarily have to win the game, if they keep it close than the number a bet on the underdog would be a winner.
A recent example of a -1.5, -2 Asian Handicap bet came in the UEFA Champions League round of 16, as Juventus hosted Atletico Madrid down 2-0 on aggregate. Juventus ended up winning the match 3-0, so if you bet them at +110 on the -1.5, -2 Asian handicap for $100, your bet would have returned you $210 (your $100 stake plus $110).