The name "Weisse Rose" (White Rose) refers to an underground organisation formed mostly by students during the 'Third Reich' - best known members were the 'Scholl siblings' - Hans and Sophie Scholl.
Both got caught and executed in 1943.
The name of the café is meant as an homage to the bravery and steadfastness the German resistance in general showed in those awful times.
The text on the board is actually uneventful - but might have been something that could have found in German cafés or restaurants of that time period:
Dish of the day
according to the supply situation
Payment in kind will be accepted.
In case of air raids immediately go to the shelter rooms beneath the theater.
Other side (facing the square):
On the terrace payment will be taken directly after service.
Sandwiches and cake only on ration coupon.
(Graffiti: Duckling was here!)