BCS theory of superconductivity explains how electrons, which are fermions, can pair up and behave like bosons under certain conditions. This pairing occurs through indirect coupling with lattice phonons, allowing two electrons to attract each other despite their like charges. As a result, these paired electrons form a new entity that follows Bose-Einstein statistics, enabling them to flow without resistance. The process is facilitated by low temperatures, where lattice vibrations create dipoles that help couple the electrons. Overall, BCS theory illustrates the transition to superconductivity through electron pairing and lattice interactions.