Relay isolation refers to the ability of a relay to electrically separate two parts of a circuit, preventing unwanted interference or damage between them. A relay, typically an electromagnetic switch, can control the flow of electricity in a circuit by using a low voltage signal to open or close contacts that handle higher voltages. The isolation provided by relays is essential in applications where different parts of a system need to be kept electrically independent while allowing communication between them. This isolation ensures safety, prevents damage to sensitive components, and improves the overall reliability of the system.