Here's why:
* Grande is the feminine form of the adjective grand, which means "big" or "large".
* In French, adjectives usually have different forms depending on the gender and number of the noun they modify.
* Since grande is feminine, it is used to describe feminine nouns, like "une grande maison" (a big house) or "une grande fille" (a tall girl).
Let me know if you have any other questions!