The primary function of a network switch is to connect various devices within a local area network (LAN) and facilitate communication between them. It operates at the data link layer (Layer 2) of the OSI model, enabling devices to send and receive data efficiently. A switch uses MAC addresses to forward packets of data to the correct destination, reducing network collisions. This enhances overall network performance by prioritizing traffic and ensuring reliable connections among computers, printers, and servers within the network.