What is a high-calorie diet?
A high-calorie diet is the opposite of a low-calorie diet, that is, you will consume more calories than your body uses.
If your body burns 2500Kcal daily and you consume 3000Kcal, you will be following a hypercaloric approach.
The same example of a low-calorie diet can be applied here, individual A spends 2000Kcal per day and individual B spends 3000Kcal per day, in a 2500Kcal diet, individual A will be following a hypercaloric diet and individual B will be following a hypocaloric diet.
Hypercaloric diets are used to gain muscle mass/weight.