Food should be healthy, that is it should have all the nutrients needed for the body. Like, carbohydrates, Proteins, Vitamins and Minerals, etc. A balanced diet is that gives your body the nutrition it needs to function properly.
A balanced diet is important because your body's organs and tissues need proper nutrition to work efficiently. Without good nutrition your body is more prone to diseases.
To achieve a balanced diet we should include fruits, vegetables, grains, meat / bean , dairy products, oils, etc.