Your question is very broad, and you may get a number of responses depending on who answers you! Healthy food should come from the main food groups (fruits, vegetable, lean proteins, whole grains, and dairy–along with some healthy fats). A healthy, balanced diet provides our bodies with the right amount of nutrients, in the right quantities, to give us energy and enable us to lead a healthy lifestyle.
There are numerous resources for you to learn about nutrition and how it impacts your health (IDEA alone has numerous articles on nutrition). Or, you may refer to a Registered Dietician for yourself to learn about what is best for you, personally. Hope this helps…