The Currency Converter is a quick way to convert between currencies for testing those applications that work with multiple currencies.
Press this button to load most recent currency reference rates from ECB (European Central Bank), before that is done it will not be possible to do any currency conversions.
The date that the rates are from will be displayed to the left of the button.
From ECB foreign exchange rates site:
From this drop down you choose the currency that you want to convert from, it contains all the currencies that ECB publishes rates for.
When the base currency is choosen enter the amount in the input field and press enter or the convert button to convert the specified amount into all other currencies.
If this check box is checked when clicking on any amount in the result that amount will be automatically copied to the clipboard.