It’s the socket for the left speaker similar to the fan socket. It can be soldered back to the board if you find the part. You can harvest it on a Macbook donor board or buy it on eBay. Any tech can solder back the socket for cheap, only six micro solder to do on this part. Don’t try to glue it on the board, the 4 front pins must make a good contact to the pads and only solder can be used in this case.