BIP39 stands for Bitcoin Improvement Proposal 39. The words are selected from a certain list of 2048 widespread English words which may be accustomed to the make a binary seed (your personal important). BIP39 and 44, However, are a Newer form of standardization of a selected list of words (passphrase) https://exactlybookmarks.com/story19427422/considerations-to-know-about-bip39-seed-phrase-generator