"AED" stand for Automated External Defibrillator . You have probably seen these units in shopping malls, airports etc.
If someone goes into sudden cardiac arrest, for every minute that goes by without defibrillation, their chance of survival drops 10%. The units are relatively inexpensive ($1,000 - $2,000) and are easy to use once you have the training.
The Red Cross "First Aid / CPR /AED for the Workplace" training class is a 7 hour class that gives you the basics.