The function of network switches in data communication is to connect devices within a local area network (LAN) and facilitate the efficient transfer of data packets. Switches operate at the data link layer of the OSI model, using MAC addresses to forward data only to the intended recipient, reducing network congestion. By enabling communication between multiple devices, switches enhance network performance and increase overall bandwidth. They can also support features like VLANs and QoS, enabling more organized and secure networking, making them essential components of modern networks.