The Korean word for "candy" is 사탕 (砂糖), which literally means either "sand (砂) candy (糖)" or "sand sugar" since 糖 (탕) can be translated as either candy or sugar. "Sand sugar" would be translated in English as granulated sugar.
눈깔 means "eye," so 눈깔 사탕 literally means "eye candy" and generally refers to round candies, some the size of eyeballs. My dictionary translates it as "taffies" or "tobbees," but I think that is because 糖 (탕) can also mean 엿, a traditional, taffy-like Korean candy. In addition to using 눈깔 사탕 to refer to round candies, you can also use 알 사탕, which literally means "egg candy."