This display is one of the various displays made by the company Lawo-Luminator-Europa Mark IV Industries GmbH. Based on its size with only 14x16 dots, it was probably used to show the route number on the side or rear end of the bus.
Driving it requires additional hardware as it only has one FP2800a onboard which has half of its 28 outputs wired to the column pins of the flip-dot elements. The additional hardware for driving the rows needs to be connected via the IDC connector.
Please also consider having a look at the parent project called Flip-The-Dot which is about documenting and driving flip-dot displays.