If you think of the surface of a wire as a field of copper atoms, the outer layer of electrons is loosely held by individual atoms. An electric potential can cause some of these outer electrons to move. While they move fairly easily, there is a small amount of work associated with moving an electron from one atom to the next. The more electrons being forced to move the more work goes into the shifting electrons. This work shows up as heat in the wire .
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I assume you need current in an electrical circuit. All components including a simple wire give out heat. they have resistance R and the formula for calculating the energy given out in watts is I X R ^2 The resistance is the constant and so if current increases more energy if produced as heat and temperature of the wire rises.