In French, we cannot use a noun without an article.
You’ll always find an article before a noun.
As you already know all nouns have a gender in French. Either masculine (nm. in the dictionary) or feminine (nf.)
The gender of the noun defines the article that need to be used:
Le for masculine singular noun -> Le tableau (the board)
La for feminine noun -> La table (the table) L’ before ‘h’ and vowels -> L’ami
Les for plural (either feminine or masculine) -> Les étudiants / Les étudiantes
Un for masculine singular -> Un stylo (a pen)
Une for feminine singular -> Une chaise (a chair)
Des for plural (either fem or masc) -> Des élèves (some students or students)
So now what’s the difference between Le/La/Les & Un/Une/Des?
Le/La/Les are called « definite articles » they define something specific
Un/Une/Des are called « non-definite articles » they define something not specific, random
See the picture below for more explanation:
And with a video of Mafalda you cannot not get it right!
Bon apprentissage !