The handicap with the positive coefficient is the underdog team. A bet on European handicap +2 for Cagliari means: If the team wins, draws or loses by 1, your bet wins.If the team loses by 2 or more, your bet loses.
Handicap 0:2 means the Away side is having 2 goals advantage before the start of the match. Handicap 0:3 means the Away side is having 3 goals advantage before the start of the match etc.