BIP39 stands for Bitcoin Improvement Proposal 39. The words are chosen from a specific list of 2048 common English words which may be used to the make a binary seed (your non-public vital). BIP39 and 44, However, are a more recent form of standardization of a particular list of words https://esocialmall.com/story4883591/the-ultimate-guide-to-bip39-seed-phrase-github