We are learning about food items and I don't really get the rule of de la, du, and de l' and also the countable and non countable items. Can anyone please explain it to me?

Thank you for using the Jiskha Homework Help Forum. First of all, don't forget the contractions of de + le = du and de + les = des

THE PARTITIVE: The idea of "some" or "any" with a noun is expressed in French by:

de + the definite article of the noun:
du papier some (any) paper
de la viande some (any) meat
de l'encre some (any) ink
des plumes some (any) pens

de, without the article, after a negative:
Je ne vois pas de fleurs. = I don't see any flowers. / I see no flowers.
Il n'a pas d'encre. = He/She hasn't any ink. / He/she has no ink.

de, without the article, when an adjective precedes a plural word:
de bonnes plumes some good pens
de vieux livres. some old books

de, with or without the article, when an adjective precedes a singular noun:
du bon papier some good paper
de bon papier (also correct)

NOTE: The words "some" and "any" must be expressed in French, and before each noun, even though they are often omitted in English.
Avez-vous du pain? Non, mais j'ai du lait et de la viande. = Have you (any) bread? No, but I have (some) milk and meat.

I gave you the simplified explanation, since you are probably in French I?

Mme