What is “economy” in CS:GO and how to manage it?

Economy in CS:GO is a system that regulates the amount of money players can spend on weapons and equipment during the game. Economy management includes:

Choosing the right weapons: players must choose weapons based on their situation and the money available.
Spending Planning: players must plan how much they can spend at each stage of the game so that they are not out of money in the next round.
Equipment management: players should consider the cost of equipment such as armor and grenades so that they don’t spend too much money in the opening rounds.
Kill participation: the more kills, the more money you can get in the next round.