BIP39 stands for Bitcoin Advancement Proposal 39. The words are selected from a certain list of 2048 common English words which can be accustomed to the generate a binary seed (your personal key). Standard recovery phrases use a particular list of 2048 words pursuing the BIP39 standard (Bitcoin Advancement Proposal https://bookmarksden.com/story19011687/an-unbiased-view-of-bip39-seed-phrase-github