Warning light I have a 2004 Volkswagen. There is a light of a triangle with an explanation mark that is lighting up. What does that mean?

STOP engine light. There is something seriously wrong so do not operate/drive the vehicle before finding and repairing whatever is causing this light to come on!

It is shown in your owners manual
& the internet has most of the dash
symbols

it means that you have a fault in your brake system
take your audi to an audidealership and have them check the abs codes (antilock braking system)
http://net.jasonpearce.com/chronicle/audiwarnings.html

bulb failure warning,check your brake lights.

This is your ASR Light (Automatic Slip Regulation) If it blinks that means the system is preventing wheel spin. If it's constantly on, the system is either turned off, of there's a malfunction in the system. If no other lights are on the dash, it could be a faulty brake light switch. There are a DOUBLE recall on this part. Ever had it done ??

Should be a Bulb Out Indicator. Check all your external lights (headlights, brake lights, turn signals) and make sure they are all working correctly.

I have the same car,It could mean that there is a light bulb out

if it look like this http://www.postimage.org/Pq8RFN0.jpg its the esp light it means you have a fault relating to that system.you need to get a diagnostic check done,there is nothing you can do i,m afraid its a dealer or specialist job.

that is your traction control. Either you pressed the traction control button it say ASR OR ESP on your console in the center next to the hazard switch.