I can read it again for you.  I will even quote it for you.
"Virtual currency bitcoin has been recognized by the German Finance Ministry as a “unit of account”, meaning it is now legal tender and can be used for tax and trading purposes in the country."

Perhaps you do not know the meaning of "legal tender"

http://en.wikipedia.org/wiki/Legal_tender
"Legal tender is a medium of payment allowed by law or recognized by a legal system"

You cannot argue that it is not legal tender.  Private money = Legal Tender (is that clear enough for you).
Bitcoin is a medium of payment allowed by law and recognized by a legal system.  Bitcoin = Legal Tender
What you fail to understand is that it does not have to be a recognized foreign currency to be legal tender.  

For it to be a "currency" it would need to meet another criteria of being "Generally accepted and widely used", which it is not yet.