While different cultures around the world have differing ideas of health and what constitutes healthy eating, there are some general agreements on how one can eat healthy.
Healthy eating includes eating enough in quantity and quality. We can think of quantity as the caloric value of our daily nutrition- most people need to eat around 2,000 calories per day, but depending on how active someone is, their age, and their body shape, they may need to eat more or less.
Eating 2,000 calories of anything isn't enough to be healthy, as the quality of what you eat is just as important as how much you eat- if not more important! Getting enough essential proteins, carbohydrates, and fats to keep your body running and repairing itself is very important. These are called the "macronutrients-" they are the major components of food that our body uses. The smaller components are called "micronutrients" or vitamins and minerals. Eating enough micronutrients is important too, and contributes to more specific functions of the body like hormonal regulation and building strong bones.
Different nations have approached this question of how to eat healthy in different ways. The United States advises that a person's diet should be about 50% fruits and veggies, and about 25% each of grains and proteins. Fats and dairy products should be used minimally. See the "MyPlate" diagram below. Finland recommends eating at least 500g of fruit and vegetables daily, and that people should try to eat only small amounts of red meat and foods with high salt and sugar. South African dietary guidelines advise the importance of being active, and that people should eat milk products, vegetables, and either eggs, chicken, or fish every day. South Korea also stresses the importance of an active lifestyle and recommends people eat a wide diversity of foods.
Most nations advise eating lean meats and avoiding too much red meat, especially those with lots of fat and/or salt. It is also very important to eat whole grains (like brown rice, whole wheat) and legumes (like beans, peas, and lentils) and lots of fresh fruit and vegetables. Try to eat a wide variety of foods and balance with physical activity.