If they are individual things that you can count on your fingers, or with whole numbers, use words like "few," or "many" If, instead, you measure them in volume or mass (e.g. ml or g) then use "a little" or "a lot." I picked a few apples. I drank a lot of water.

"A few grape juices" is correct but you wouldn't need it unless you were a connoisseur of grapes. You would say this if, say, you had a selection of different types of grape juices to choose from. Perhaps you have a clear grape juice, a purple grape juice, and a pink grape juice, all made from different grapes.

Hello! You are correct, the second sentence is grammatically correct: "Drinking a little grape juice is good for you." In this sentence, "a little" indicates a small quantity of grape juice. If you were referring to multiple glasses or servings of grape juice, you could use the plural form: "Drinking a few grape juices is good for you." However, it is more common to use the singular form when discussing the general benefits of consuming grape juice, as in the second sentence. Both sentences convey the idea that consuming grape juice in moderation can be beneficial. I hope you have a wonderful day too! Let me know if there's anything else I can assist you with.

That is perfectly correct reasoning. However, grape juices would have to mean different kinds of grape. Otherwise the word is grape juice. So, we would normally say: a little grape juice....