There are different types of currencies (different monetary units) in the world. For example, in some countries in Latin America, the peso is used, in others the dollar, and in several European countries, the euro is used.
Each of these monetary units is composed of smaller units. For example:
In one peso there are cents or centavos.
In one dollar there are cents or penny.
In one euro there are cents.
There are also exchange rates that allow us to convert amounts from one currency to another. Like the conversion between the peso and the dollar or dollar and euro.
For example, the exchange rate between the dollar and the Mexican peso today is:
dollar Mexican pesos.
Or, in words, one dollar is worth Mexican pesos.
Note that we have written that this is its value today, as the exchange rate varies constantly influenced by many economic factors. This topic is really interesting, but it is not related to our article.