Is also the abs light lit up on the dash?
The exclamation point on the dash with the circle around it is the light to have your front brakes inspected, either because they are too low and need to be changed or the wires for the sensor have been broken.
The brake light when it flashes will normally mean either you are driving with the emergency brake pulled up or the brake system is low with fluid ( when your brake pads get low in material the brake fluid will be pushed further into to the brake caliper so the fluid will drop in the resivior)
So, you may have more than one issue.
Normally when the eclamation light is on you will need to have your front brakes inspected.
However when you have the BRAKE light on and flashing and the ABS light on solid, there is normally an issue with the abs system. You will need to have the fault codes read out. However your generation passat have issue's with ABS control modules, so reading out the faults may not be possible. The only remedy is to replace the ABS control module if you cannot communicate to the ABS control module.