The switch has a CAM (Content Addressable Memory) table which has mapping of the ports and MAC addresses of the computing node that is connected to each port. The switch learns the MAC address of the nodes initially when it is sending data on the port. The first frame from each node is always broadcasted across the switch to all other nodes known as Broadcast Mode. By time, the switch will have all the MAC addresses mapping to the port, they are connected. Once the switch has complete CAM updated, if a node wants to send data to another node, the switch will get frame from the sender node through the sender connected port and put the frame on the receiver connected port. to the receiver node as it has the MAC address mapping. This is known as Unicast Forwarding Mode.
