BIP39 means Bitcoin Advancement Proposal 39. The words are selected from a particular list of 2048 prevalent English words which can be used to the produce a binary seed (your personal essential). Standard recovery phrases use a certain list of 2048 words following the BIP39 standard (Bitcoin Improvement Proposal 39). https://bookmarkprobe.com/story19109237/a-secret-weapon-for-bip39-words-to-numbers