It looks as though mains AC comes in at left. And I think it filters power to an appliance at right. I'm reminded of a store-bought 'noise filter' which I took apart. It claimed to improve radio and tv reception as well as reduce hum coming through my audio equipment. Inside I found a capacitor and coil of fine wire. Not too complicated. Maybe it even worked, though I don't recall it made that much difference.
Your schematic is more complicated of course. It has similar components and they're arranged in a fashion to function as a filter.