What does the dashboard warning light with a shoe in a circle mean on a VW Jetta?

That's the ASL (automatic shift lock) indicator light.

"Your VW is equipped with an automatic shift lock (ASL). The ASL is an electromechanical device that locks the selector lever in the park and neutral positions when the ignition is on.

You must press the brake pedal before the selector lever can be moved out of either position."