Electricity will flow through many kinds of wires without making them glow. The wire in a filament is different. The wire is very thin and so electricity has to push hard to flow through it. As it pushes some of its energy changes to light and heat.

The filament is coiled to give it greater length. If the filament was just a piece of straight wire it would only give out a small amount of light. By curling the wire into a coil, a very long length of wire can be stored in a small space. When electricity flows through the coil it can give out much more light.