BIP39 means Bitcoin Advancement Proposal 39. The words are picked from a certain list of 2048 frequent English words which can be used to the crank out a binary seed (your non-public important). Standard recovery phrases use a particular list of 2048 words following the BIP39 standard (Bitcoin Advancement Proposal https://bookmarklinkz.com/story18740283/little-known-facts-about-bip39-seed-phrase-list