When do you use la, le, l' or les?

These are called the definitive articles and they are used to replace the English word 'the' before a noun. They distinguish the noun as being masculine, feminine or plural. 'la' is followed by a feminine noun for example, 'la table' meaning 'the table'. 'le' is followed by a masculine noun for example, 'le livre' meaning 'the book'.'l'' is followed by a noun that begins with a vowel or the letter h for example, 'l'eau'.'les' is followed by a plural noun for example, 'les livres' meaning 'the books'.