What's the difference between "Il a du vin" y "Il a vin" what's the use of the word "du"
yes, "il a vin" is not acceptable. "Il a le vin" is techically acceptable but the french do not think this way. If you said "Il a le vin," they would think you mean you have all the wine in the world, but when you say "il a du vin," du technically means some so you are saying you have some wine, which is more practical in their minds.
Jdc you could also use it when for example looking at someone's list and mainly talking about the words rather than the actual thing they describes. So ... on that list (he has) il a vin, bière , liqueur, jus de fruit etc. But yes it's not a usual way to speak. (Comme ca c'est un peu 'couper les cheveux en quatre'!)
To put it in a few words: "du" is used for an undefined, unspecified amount. Example in English: "If you pass by the supermarket, please bring apples, too!" Or: "...bring some wine too!"
In french, an article such as le, la, les, de, du, de la, etc. is almost always necessary. "Il a vin" is not possible. The word "du" is the combination of the two articles "de" and "le" and it translates most of the time as "some".