Difference Between "Natural" and "Added Sugars"
The sugars listed on the Nutrition Facts panel on foods include BOTH naturally occurring sugars (like those in fruit and milk) as well as those added to a food or drink. Naturally occurring sugars are NOT considered "added sugars."
Below is a comparison the U.S. Food and Drug Administration provided on two yogurts.
The plain yogurt on the left has no added sugar; the other one does. Depending on your overall food choices and calorie needs, either one might be a satisfactory choice. Just be aware that when a dairy or fruit product cites "sugars" on the Nutrition Facts panel, it doesn't mean there are added sugars, unless a form of sugar listed in the ingredients.
Plain Yogurt: contains no added sugars
Ingredients: cultured pasteurized grade A nonfat milk, whey protein concentrate, pectin, carrageenan
Fruit Yogurt: contains added sugars
Ingredients: cultured grade A reduced fat milk, apples, high fructose corn syrup, cinnamon, nutmeg, natural flavors, and pectin