Macronutrients are what your food is made up of and there are 4 different types:
Protein- think rebuilding and recovering
Fats- absorbs vitamins essential for survival
Carbohydrates- fantastic for performance and accelerating recovery
Alcohol- makes you do stupid things
Only look into macronutrients once you are hitting your calorie target regularly for at least 21 days.
Depending on your goal your macronutrients will vary.
If your goal is to build muscle then your macros should start as follows:
High protein 35-45%
Low fat 15-25%
High carbs 40-50%
If your goal is to burn fat then your macros should start as follows:
High protein 35-50%
Low fat 20-35%
Low-medium carbs 25-45% consumed around training