It's the adapter for the factory fit phone kit. You had to buy an additional cradle for your phone but the available cradles were so out of date, not even sure if you can still get them.
I had this kit on my car when I bought it. I used it for a while as I had a Nokia 6230i so the dealer threw in a cradle as part of the deal. When I changed phones I installed the Skoda bluetooth kit so the factory fit one became redundant. I eventually removed it but you need a new glovebox as the adapter bolts through the fascia. Glovebox is quite easy to change.