HTTP Status Code 504 indicates Gateway Timeout, which occurs when a server acting as a gateway or proxy does not receive a timely response from an upstream server it needs to access in order to complete the request. This status code tells the client that while the gateway was able to connect to the upstream server, the response took too long, leading to a timeout situation. When a server returns HTTP Status Code 504, it suggests that there might be issues with the upstream server or network connectivity. Users encountering this status code should be aware that the issue is not with their request but rather with the server's inability to communicate effectively with another server in the chain.