How do exchange rates for valuta work?

Once in Economics class, years ago, my teacher was telling about exchange rates. She told us that if you go on holiday to any country, you have to change your Euros [I'm European] to the valuta you need in that country, because you will get more money than if you would have done that back home. And that if you go back, you have to change your left-over foreign money from your trip back to Euros in a Euro country, also because that is supposed to be cheaper than changing them to Euros in the country you just came from.

I have a simple question - is this correct? If it is, tell me how that works, please. If this isn't correct, also please tell me how that works.

I'd be delighted if you'd be able to answer them for me. If this isn't the subreddit I should be on, please direct me to the one where my questions will be answered.

Submitted August 08, 2015 at 10:16PM by WritingReferences http://ift.tt/1f0XV24