what does that mean?
A business with either a very long history of being in business (sometimes for generations) or a business working wit traditional working methods. Should tell you: we are very experienced, focused on high quality and, since we're so old, we must be very good, else we were out of business a long time ago.
Then again, it is advertising, so you have to find out yourself if it is true
Traditionsbetrieb (m) traditional (oder long-established) business