According to an online translator:
"This message was set of eBay in the name of a eBay member by "my messages". Their answer is sent by E-Mail directly to the eBay member and contains automatically your E-Mail address. If you liked to send your answer, without your E-Mail address is along-sent, click please down to now to answer."
It's just the generic message saying that you've received a message from an Ebay member. It's warning you that if you reply by email, your email address will be visible. So if you don't want them having your email address, click the link to reply through the Ebay messaging system.