From the pic it is hard to tell what size this plow is. Maybe a plow for a garden tractor?
Also, from the pic, it is hard to see what is attached to what, without a better angle to get a 3d dimension. But the crank looks to be connected so it can adjust the possition of the front hookup. I suspect it has to do with adjusting the forward/aft or pitch of the plow (relative to the tractor) to point the 'nose' of the plow into the ground (a form of depth control). Just a guess. It appears this plow is possibly hooked to a drawbar, and the 'frame' on top attaches to a hydraulic or mechanical lift mechanism (like Allis Chalmers used to have). Appears the plow doesn't attach to a 3pt system.
As I say, just a guess. Any idea the brand?
When I first saw the pic, I was thinking it (top frame) might be a 'drawbar' for a drag hanging out to the side to knock down standing dirt clods and keep soil moisture in. But on closer look, the 'frame' appears to not be integral to the crank assembly sticking out to the rear.