These have pointed ends that stick out into the grass and guide it into the spaces between the guards. They also have serrated plates that the moving bar rides on. The grass gets caught between the fixed and moving serrated plates and gets cut. Mowing is a brain dead occupation - almost. You drive around and around a piece of hay land until all of the grass is cut.
Square patches are fun because there is a trick to cutting square corners.
The tractor has separate brakes for each wheel. There is one other piece of equipment you need for haying - the rake. What you need for making hay is a rake trailing the tractor to gather up the grass as it's cut. And it is later on. You don't make hay with green grass.