The preposition "à" in French is commonly used to indicate direction, location, or time. It translates to "to," "at," or "in" in English, depending on the context. For example, one might say "Je vais à Paris" meaning "I am going to Paris," or "Je suis à la maison" meaning "I am at home." Additionally, "à" is used to express possession or relationships. For instance, "Le livre est à Marie" translates to "The book belongs to Marie." It can also indicate a specific time, as in "à midi" meaning "at noon." Understanding "à" is essential for constructing meaningful sentences in French.