In economics, goods are things that fulfil people’s needs and wants. Basically, anything that gives you some kind of benefit can be called a “good.”.
Now, when we talk about money, it’s like a tool (medium of exchange) we all agree to use for buying and selling things. Different types of money (like currencies) have their own value and are accepted in different places. The value of money compared to other types of money can change because of what’s happening in the world.

While it can be used as a tool to acquire goods, money in itself can actually be a type of good as well. You can trade one type of money for another, just like you’d swap one thing for another in a regular sale. Consider the scenario below to understand how this could happen.

Imagine Alice wants to trade her US Dollars for some Euros, and she thinks each Euro should be worth 1.4 US Dollars. On the other hand, Bob wants to trade his Euros for US Dollars but believes each Euro is worth 1.6 US Dollars. The actual market price is 1.5 US dollars per Euro.

The problem here is that there's no agreed-upon rule for how much one currency should be worth compared to another. This lack of a clear rule makes it tricky for people like Alice and Bob to agree on a fair price when exchanging currencies. To make these exchanges smoother, we need a system in place to control and manage them, and that's where centralization comes in. 

Centralization means putting someone in charge to make sure currency exchanges are fair. Usually, currency exchange companies take on this responsibility, working with the government to make sure the value of the various currencies are regulated. But there’s a twist; figuring out how much one currency is worth is tied to how a country’s government or central bank manages its money, and that’s another can of worms.