'The rest'. The renowned Hogwarts School of Witchcraft and Wizardry is populated by students of four great houses. Gryffendor for the bravy, Ravenclaw for the wise, Slytherin for the cunning and Hufflepuff for ...the rest.
Hufflepuff does indeed have its moments of achievement. For instance, one of their members was killed last year. Something all students in Hufflepuff can aspire too!