BIP39 means Bitcoin Improvement Proposal 39. The words are picked from a specific list of 2048 prevalent English words which can be accustomed to the produce a binary seed (your private key). Standard recovery phrases use a certain list of 2048 words pursuing the BIP39 standard (Bitcoin Enhancement Proposal 39). https://single-bookmark.com/story18906850/top-guidelines-of-bip39-word-list-pdf