As with many cars, the EML on a BMW is the engine management light. When the engine management light shows on a dashboard, it means the computers aboard the car have detected a problem with the engine.
If the EML light appears on a BMW but there is no other indication of engine trouble, the driver does not need to pull off the road immediately. The EML can indicate a whole range of problems, some of which may be serious while other are very minor. When possible, the driver should take the car to a qualified BMW mechanic to have the EML reset. While resetting the EML, the technician also checks the fault codes to see what issue occurred to set it off. If the car is displaying other obvious engine problems when the EML light goes on, the driver should pull over and deal with those problems right away.