Learn French: Est-ce que toutes les filles sont prêtes ?

The word tout (all) must match the gender and number of the noun it describes. Because filles (girls) is a feminine plural noun, you must use the feminine plural form, which is toutes.

Why is the word les included between toutes and filles?

In French, you must use a definite article (le, la, l', or les) after tout when talking about all of a specific group. Even when English just says 'all girls' in a general sense, French requires toutes les filles (literally: all the girls).

Why does the word prêtes end in -es?

Adjectives must match the gender and number of the noun they describe. The base adjective is prêt (ready). Since it describes les filles, we add an -e to make it feminine and an -s to make it plural, resulting in prêtes.

Do you pronounce the -s at the end of toutes?

No, the -s at the end of the feminine plural toutes is silent. You pronounce it just like the singular feminine form toute.