Exchange rates is the amount that it takes to make $1.00 in the United States
Example - say you had paso's it may take 10 paso's to equal $1.00 in US $ - (this is not the exchange rate it is an example of how you get to the exchange rate)
Example 2 - say you had paso's (from South America say Peru) the $ value in Peru is poor so it could be as such - 10,000 paso's = $1.00 in Us dollars
I hope this helps you understand the concept better