BIP39 means Bitcoin Advancement Proposal 39. The words are picked from a particular list of 2048 common English words which can be used to the generate a binary seed (your non-public crucial). Standard recovery phrases use a specific list of 2048 words following the BIP39 standard (Bitcoin Advancement Proposal 39). https://bookmark-share.com/story19037596/how-much-you-need-to-expect-you-ll-pay-for-a-good-valid-bip39-seed-phrase