This is an Interfit STR114 Sony/Minolta Hot Shoe Adapter. Many years ago, Minolta decided to redesign the hot shoe on its cameras to provide a more secure way of mounting a flash. Even though it was a good design, no other manufacturers changed from their "Standard" hot shoes.
This adapter permits mounting of Interfit, or any other standard non-TTL flash, or flash accessory onto a Sony/Minolta camera. It also has a PC terminal to add an additional accessory.