BIP39 means Bitcoin Improvement Proposal 39. The words are selected from a specific list of 2048 common English words which can be utilized to the create a binary seed (your non-public critical). Standard recovery phrases use a particular list of 2048 words following the BIP39 standard (Bitcoin Improvement Proposal 39). https://yesbookmarks.com/story19121628/the-invalid-bip39-phrase-diaries