"Le" is a definite article in the French language, equivalent to "the" in English. It is used to specify a singular masculine noun, indicating that the noun is known to the listener or reader. For example, in the phrase "le livre," which means "the book," "le" identifies a specific book. In French grammar, articles like "le" are essential for sentence structure. They help clarify meaning and provide context. There are also other forms of the definite article, such as "la" for feminine nouns and "les" for plural nouns, which are used in different situations to match the gender and number of the noun.