A network switch serves as a central device in a computer network that connects various devices, such as computers and printers, allowing them to communicate. It operates at the data link layer (Layer 2) of the OSI model, using MAC addresses to forward data to the correct destination. By creating a dedicated pathway for each communication, network switches enhance efficiency and minimize collisions. They facilitate local area networks (LANs) by segmenting traffic, improving network performance and scalability as organizations grow.