An attack is a single attack on a single target that flips over a single attack modifier card. If your attack action is, say, "Attack 3," then there is only one attack in your attack action. If it is "Attack 2, Target 3," then your attack action consists of three separate attacks. If the action contains separate "attack" lines, all are part of the attack action. If the attack is an AoE, all attacks performed as part of the AoE are part of the attack action.