BIP39 stands for Bitcoin Advancement Proposal 39. The words are selected from a particular list of 2048 frequent English words that may be accustomed to the generate a binary seed (your personal critical). This post explains BIP39, the standard that defines how seed phrases are made, and summarizes how BIP32 https://socialeweb.com/story4291369/the-definitive-guide-to-bip39-seed-phrase