Second only to the World Cup (for Europeans), the Euro Cup is a really big deal in the countries that sponsor participating national teams. Germany is, of course, one of those nations and you will hear your host families talking about the tournament while you are there.
Do a little study about the tournament before we leave, so that you can appreciate their excitement and understand a little bit about how the tournament is configured.
Here's a link to a nice Wikipedia article that summarizes the 2012 Euro Cup, and gives you all the 'need to know information.'
Here's a link to the official UEFA site, for you more serious football/soccer fans!