There are a bunch of great resources on the web for what stuff means. I ran into a bunch of heady explanations for the word lumens, however the one that made the most sense to me came from lightsandknives.com.
In a nutshell, if you’re going to measure something, you need a frame of reference. So people use the candle. Also, we know that light gets dimmer the farther away you go, so to measure how “bright” something is you need to factor in distance. Finally, “brightness” can be effected by the shape of the light. Basically how much light is cast over an area. It makes sense that a beam is more “intense” than a naked candle flame. If you’ve ever had one of those Ever ready lantern / flashlights you know exactly what I’m talking about. In flashlight mode you can’t stand to look at it, but in lantern mode it is comfortable to stare at the naked bulb.
So the three components of measuring how bright a light is are the intensity of the source, how far away you are and how much area is being illuminated. The metric standard is to measure one candle, from one meter away and see how much light is cast on a 1 meter area.
A 60 Watt bulb casts 800 lumens if that gives you an idea.
Scott