Why does international trade require a system for exchanging currencies between nations?

International trade is the exchange of products between different countries of the world. Some countries produce certain resources in a surplus way, while other countries need these products and cannot produce them or do so on a small scale.

As each country has its own currency, different from that of the other countries (except in cases of common currency such as the Euro in the European Union, or countries that have the Dollar as currency, such as Panama or Ecuador) and with a reference value that It corresponds to the reserves and monetary policies of its central banks, it is necessary that there is a means of exchanging these currencies.

That means is the exchange value system, by which each currency has a reference value in dollars, so that they can convert one currency to another without major inconveniences.

i don't know the answer to this