A light bulb is simply a small metal wire that is glowing with heat. This is important because tungsten is solid at very high temperatures. A light bulb also has most of the air sucked out of it. If it didn't, the wire would actually burn up instantly. Now back to how a lightbulb works.
Electricity flowing through the wire causes it to heat up.
This heat makes it glow. It heats up because of a concept called resistance . When electricity passes through something, the substance it is passing through tries to hold on to the electrons. The electrons have to be forced through. Some of this force is absorbed by the metal and given off as heat.