In singular form, when a word has '"la/le" as determinant, it becomes "les" in plural form. If it's "une/un", then it becomes "des". You then have to add an "x" or "s" at the end of the noun, depending on the word. Don't forget to change the adjectives too.
BUT, some words in french don't change whether they're written in plural or singular form so you have to be careful with that.
Determining the gender of "un professeur," for instance, requires the knowledge of whether the teacher is a man or a woman.
- true
Un professeur = masculin
Some words are always masculine or feminine, despite the gender of the person referred to. Don't be tempted to select the article you use based on the gender of the person about whom you are speaking.
