I believe that is in fact a "snorkel" (sounds good to me).
That would allow you to take the vehicle into water to a level higher than if you didn‘t (lest water get into the air-filter, engine, etc).
I don‘t know the spec‘s on how deep of water it can ford, but it what be better than that of the Iltis it is replacing. I "swam" one once in a long shallow puddle. Kind of fun until the water started filling the vehicle through the little holes in the floorboards.
If you look at the LandRovers, etc that other nations use, they have similar setups. I think I‘ve seen it on civvy pattern SUV‘s that NGO‘s and others use.
Al