How exchange rates are set
Currency exchange rates float based on global supply and demand — trade flows, interest rate differences between countries, and investor sentiment all push a currency's value up or down against others, continuously, during market hours. The rate you see here is a daily reference rate, which is a snapshot rather than a live tick-by-tick trading price.
Reference rate vs. the rate you'll actually get
Banks and money transfer services almost always add a margin on top of the reference rate, plus sometimes a flat fee — so the amount you actually receive when exchanging money is typically a bit less favorable than the "mid-market" rate shown by a converter like this one. Use this tool to understand the fair baseline, then compare it against whatever rate your bank or transfer service quotes you.
A quick example
If 1 USD = 0.92 EUR, then converting $500 gives €460. If your bank quotes you 0.90 EUR per dollar instead of 0.92, that 2-cent gap per dollar is effectively their fee — on $500, that's $10 you wouldn't have lost using the mid-market rate as your reference point.