Just like in English, the plural in French is usually marked by an S at the end of the word. But it is silent. The article will also change in the plural form.
Le and la become les. Un et une become des.
The plural in French can sometimes be marked by a x at the end of the word. This is true for nouns ending in eu, eau and au.
For a more detailed and advanced version of this lesson, please see our weekly lessons series.