BIP39 means Bitcoin Enhancement Proposal 39. The words are selected from a certain list of 2048 widespread English words which may be accustomed to the deliver a binary seed (your personal essential). Standard recovery phrases use a selected list of 2048 words pursuing the BIP39 standard (Bitcoin Enhancement Proposal 39). https://moodjhomedia.com/story2582441/how-much-you-need-to-expect-you-ll-pay-for-a-good-valid-bip39-seed-phrase