This is the connector for the harness that connects to the transmission reverse light.
Depending on your old VWs transmission and year, it could be one of 3 different kinds of switches.
There is a great explanation here:
http://www.brokevw.com/reverseswitch.html
This connector was designed to work with these female pins:
https://www.amazon.com/gp/product/B00ACD9SQ2/
If you're missing the connector and or harness, you can rebuild it with this part
Note: I added the piece to be able to pull it up easier.