What is the secret recovery phrase in MetaMask?

Excuse me, could you please clarify what the secret recovery phrase in MetaMask refers to? I understand MetaMask is a popular cryptocurrency wallet that allows users to store, send, and receive digital assets, but I'm not familiar with the term "secret recovery phrase" in this context. Is it a unique set of words or characters that can be used to regain access to the wallet if the user forgets their password or loses their device? If so, how important is it to keep this phrase secure and private? Thank you for your time and assistance.