"Les petites filles lisent un livre."
petit = used for masculine nouns
petite = used for feminine nouns
Add an "s" to either for plural
There is an audible difference between "petit" and "petite". There isn't really an audible difference between singular and plural, unless the word after petits/petites starts with a vowel...then you get a "Z" sound between the two. Like "Les petites amies" would sound like "les petite Zamies". I don't know if I explained that clearly. Hope it helps somewhat!