The abbreviation AED stands for Automated External Defibrillator. It is a portable device used in CPR when someone is in cardiac arrest.
In a cardiac arrest, the heart usually does not stop completely. It just seems so. The heart chambers are stimulated very quickly and chaotically, so that they no longer contract. This is called ventricular fibrillation. An AED is then needed to reset the heart and allow it to beat normally again by means of an electric shock. This resetting of the heart rhythm is called defibrillation.
All AEDs that you buy in the Netherlands have a CE mark and are safe and reliable. An AED can differ in ease of use.