The term 'macros' is thrown about all the time in the health and fitness industry but all it actually stands for is 'macronutrients' - these are nutrients that are needed in large amounts in our body for daily functioning. The 3 main macronutrients are:
1) Protein - essential for building muscle mass
2) Carbohydrates - converted into glycogen in the body and used for energy
3) Fat - another source of energy and important for a number of bodily functions.
Regular gym-goers often track their macros to make sure they are getting enough of each nutrient in their diet in order to optimise their results. For many, protein is on the top of the list because it is so crucial for building muscle and it is also great for keeping you full for longer as it takes longer for the body to digest. Carbohydrates are also closely tracked because they are the preferred energy source for the body. This means that if we are doing lots of exercise then we need to make sure we are re-fuelling our body correctly so we don't feel tired and sluggish. Finally, dietary fat is also tracked as it another source of energy for the body and it is fundamental to a lot of important bodily functions.
How much of each macronutrient you should be eating is completely dependent on the person - their height, weight, energy level, body composition, hormones and so on. This means you should NOT just follow guidelines which have been made for someone else because we are all unique and what works for your friend might not work for you. In the same way, macro calculators you can find online won't always be accurate for your own needs so it's important to take them with a pinch of salt.
Do you need to track your macros? Well that completely depends on your goal. People that want to compete in bodybuilding competitions generally need to track their macros because they are working towards such a specific goal weight. However, for the normal person like you and me, whilst it's probably not necessary to track your macros everyday it is still good to have a general idea of what you are eating. Because I train in the gym most days I need to make sure I am getting enough protein because it is essential for muscle repair and recovery. But do you NEED to track them? In short: no. But you can if you want! As always, just find what works best for you :)