What is "2DIN" in the context of car radio interfaces?
There is an old standard for car radio mounting, it's called the “DIN-Schacht” or “DIN slot“ (simply translated from German). In the past, all German car manufacturers (and a lot of other, too) had one or two of those slots installed in every vehicle, so you could easily fit in a third-party car stereo, a CB radio, a trip recorder or taxi meter in the car.

2DIN is a special case of two slots directly above of each other, so either two standard-height or one 2DIN appliance fits. Unfortunately, this standard isn't nearly as widespread as the DIN-Schacht was, so you have to check your car manual if that thing would fit. Unlikely, but worth a try.