Bitcoin Improvement Proposal 39 (BIP-39) defines a list of 2048 words used to create 12- or 24-word mnemonic phrases, often called seed phrases.

A seed phrase is not itself an account or a private key. It is a backup phrase that can recreate a whole set of accounts. Think of it like the root of a tree: each branch leads to a different account with its own private key and address. The same phrase recreates the same tree every time.

You can derive public addresses from those accounts, but you cannot work backward from an address to the seed phrase.