"Il y a des pommes de terre."
Translation:There are potatoes.
I can understand There are potatoes in answer to a question -"What's left for dinner?""There are potatoes" or as a fragment - "Let's see, there is butter, there are potatoes - we'll make mash!" but not in isolation. English looks for something to round off the sentence (especially with indefinite nouns) such as: "There are potatoes there.""There is a car (over) there""There is a cloud up there/in the sky/across the moon etc
"There are some potatoes" is another correct interpretation. Keep in mind that "des" does not necessarily translate to "some". Des is the plural indefinite article that doesn't exist in English. It is the plural of un/une. At times we can translate it as "some" but usually we just say the plural word in English without any article.
une pomme de terre = a potato
des pommes de terre = potatoes