BIP39 stands for Bitcoin Improvement Proposal 39. The words are selected from a specific list of 2048 prevalent English words which can be used to the make a binary seed (your private vital). Standard recovery phrases use a certain list of 2048 words following the BIP39 standard (Bitcoin Enhancement Proposal https://techonpage.com/story4428952/bip39-phrase-generator-can-be-fun-for-anyone