Introduction to Macronutrients
Macronutrients provide calories. They are divided into three main groups according to their chemical structure. Sometimes we shorten to just “Macros”
They are: Protein, Carbohydrates and Fats
Here are some examples of which foods have which macronutrients:

Many people talk about Macros and some understanding is helpful for many people.
Your personal trainer, nutritionist or dietitian may suggest a goal for each macronutrient to reach a goal.
This is great as you can eat with more freedom than a meal plan.
However this does somewhat oversimplify things occasionally. This is because many foods could technically fit into your macro allowances and not be very healthy!
I always recommend bearing in mind your micronutrients (vitamins and minerals) when planning your meals and choosing unprocessed foods when possible for extra fibre.
Note:
Alcohol is technically another macronutrient. However it is not essential :( If you are counting macros, you may find that many apps allocate alcohol to the Carbohydrates.