Car LED headlight bulb with a rating of “350” refers to the luminosity output of the bulb in units of lumens. Lumens measure the total amount of visible light emitted by a source. A higher number of lumens means a brighter light output. So, a car LED headlight bulb with a rating of 350 lumens will produce a brighter light than one with a lower rating. The actual power consumption of the bulb may be different and is typically specified in watts.