Okay kiddo, EN 14214 is basically a very important rulebook that tells people how to make a special kind of fuel called biodiesel. Biodiesel is made from natural materials like vegetable oil or animal fat instead of using oil that comes from underground like diesel fuel. This is really good for the environment because it doesn't create a lot of pollution.
The rulebook, EN 14214, tells people how to make sure that the biodiesel they make is safe to use in things like cars and trucks. It makes sure that the fuel has the right amount of things like chemicals and water in it so that it works properly and doesn't harm the engine. That's why it's really important that people follow this rulebook very carefully when they make biodiesel.