Harry Potter Herbology Class. In the Harry Potter books and movies, Harry attends a class on herbology taught by Professor Sprout. In the game, first years don't take herbology.
Herbology is the study of magical and mundane plants and fungi.
In Herbology, students learn to care for and utilize plants, and learn about their magical properties, and what they are used for.
The subject is depicted as closely related to Potions, due to the nature of the plants, many of which are cultivated for extracting useful ingredients. I guess Herbology could be fun, learning about plants with magical properties, but whether a student enjoys it or not, it's a required class at Hogwarts for the first five years. Unlocking Gillyweed lesson requires earning a total of nine stars from Herbology classes.