BIP39 stands for Bitcoin Enhancement Proposal 39. The words are selected from a selected list of 2048 common English words which can be accustomed to the produce a binary seed (your non-public important). This text explains BIP39, the standard that defines how seed phrases are created, and summarizes how BIP32 https://exactlybookmarks.com/story19560843/little-known-facts-about-bip39-words