It displays the food you have eaten, the calories the food contains per serving and nutrition facts about the food. It shows you how much calorie you have already consumed for the day.
Your daily recommended calorie intake is computed using the Harris-Benedict Equation which takes into consideration your age, gender, height, weight and your activity type (sedentary, lightly active, moderately active, very active, extra active).
It could also help you keep track of your weight.
The food data used in this application are taken from the U.S. Department of Agriculture, Agricultural Research Service. 2014. USDA National Nutrient Database for Standard Reference, Release SR27. Nutrient Data Laboratory Home Page, http://www.ars.usda.gov/nutrientdata.