BIP39 stands for Bitcoin Enhancement Proposal 39. The words are chosen from a particular list of 2048 frequent English words that may be used to the create a binary seed (your personal key). Standard recovery phrases use a certain list of 2048 words pursuing the BIP39 standard (Bitcoin Enhancement Proposal https://thejillist.com/story8922139/the-ultimate-guide-to-bip39-seed-phrase-github