All we can tell you that it is part of the window's track, but we need to replace it. If you can, can you tell us the name and what it does so we can replace it.
Casey from SWISCO responded:
July 11, 2019
Hello,
The guide in your picture resembles one of our hinge sets. Take a look at the 36-048 and see if the dimensions match up to your part. Thank you!