This lecture covers the concept of electric potential, starting with the definition of the potential function for a point charge and its relation to potential energy. The instructor explains how to calculate the work done on a charge when moving it from infinity to a specific point, emphasizing the importance of the potential function. The concept of equi-potential lines is introduced, illustrating how the gradient of the potential function points in the direction of maximum increase. The lecture concludes with the calculation of the energy of a system of continuous charge distribution, highlighting the formula for the total energy of the system.