A network switch plays a crucial role in a computer network by connecting devices within that network. It receives incoming data packets, processes them, and forwards them to the appropriate destination device. Operating at the Data Link Layer, switches use MAC addresses to make intelligent decisions, improving network efficiency and reducing collisions. They can support various devices, such as computers, printers, and servers, facilitating communication in both local area networks (LANs) and larger networks, enhancing overall performance and reliability.