BIP39 means Bitcoin Improvement Proposal 39. The words are selected from a certain list of 2048 frequent English words that may be used to the make a binary seed (your non-public crucial). Standard recovery phrases use a specific list of 2048 words adhering to the BIP39 standard (Bitcoin Advancement Proposal https://1001bookmarks.com/story18732126/the-invalid-bip39-phrase-diaries