Attacking the enemy Meowmon

Once you are in a battle, you can click the "Attack" button to attack the enemy. A regular attack will decrease the enemy's HP by the amount of Attack Damage that your Meowmon has.

That means, if your Meowmon has 5 Attack Damage and the enemy has 50 HP, attacking will reduce the his HP by 5 - resulting in 45 HP.

However, when striking an enemy, in the same moment, his Meowmon will attack you back as well, then reducing your Meowmon's HP by the amount of Attack Damage of his Meowmon.