Potion are mixtures of stuff to creating liquid to have different effects.  Witches, Spellmasters, and Earth Priestesses have the ability to brew potions.  Benny brought three potions to Ethan to see which one was the

Benny with potions

Revival Potion.  Benny used the Revival Potion to resurrect Puffles to get Delia to like him and go out with him.  Benny brewed a Love Potion to make Erica fall in love with him which resulted in every girl in school liking both him and EthanGrandma brewed a potion to reverse the effects of the Revival Potion and incinerate the reanimated bodies. 
Ethan with the potion

Ethan holding the Revival Potion

Love potion

Love Potion

Grandma brewing a potion

Grandma brewing a potion