MASCULINE AND FEMININE - SINGULAR AND PLURAL
You'll recall ARTICLES 01, which explains how all nouns in French are either male or female. Quite straightforward, once you get the idea. What about plurals, where you have "more than one" of something? In French, there's a different word for "THE" for plurals, too. "le" is masculine singular for "the" (as you know). "la" is feminine singular for "the" (which you also know).
"THE" (plural, referring to more than one of something) is "les". The plural of "le" is "les". And the plural of "la" is "les" (as well!).
So we have "le livre" (the book) and "les livres" (the books);
"la table" (the table) and "les tables" (the tables).
"the girls" = "les filles", and "the boys" = "les garçons".
You'll find *lots* of different vocabulary words here. All of them should have a "le" or a "la" with them, to tell you if they're male or female (masculine or feminine). On the few occasions where the noun starts with a vowel (a, e, i, o, or u, and occasionally an unsounded "h") you might find "l'" instead of "le" or "la". There should be a (m) or a (f) afterwards, to tell you whether that noun is masculine or feminine. Same with "les" ..... you *always* need to learn whether the basic noun is male or female.