A picture says more than a thousand words.
The hanger is wide and distributes the weight of the suit over a much larger area than regular hangers. It is considerably more gentle on the suit and gives extremely little strain on the material compared to narrower hangers.
Suits weigh a great deal, and the width + physical size of the hanger is both useful and necessary to minimize wear on suit fabric in connection with drying and storage.
An alternative is the HP-hanger you can find elsewhere on this site.