Question

when energy travels through a wire and lights a bulb what is happening

Answer 1

electricity is flowing through the circuit

Answer 2

The electrons enter the light bulb filament with relatively high kinetic energies. As they travel through the filament they collide with metal atoms transferring much of their kinetic energy to the metal. This energy raises the temperature of the metal. The metal in turn radiates this energy as electromagnetic waves, many in the visible spectrum.

and

Each light bulb results in a loss of electric potential for the charge. This loss in electric potential corresponds to a loss of energy as the electrical energy is transformed by the light bulb into light energy and thermal energy