Bip39 Passphrase. Entropy values have to be sourced from a solid source of randomness. This implies flipping a fair coin, rolling a good dice, sounds measurements etc. Do NOT use phrases from books, lyrics from music, your birthday or steet tackle, keyboard mashing, or something you're thinking that is random, https://oteldirectory.com/listings13062078/bip39-checksum-https-linktr-ee-bip39-5-simple-statements-about-bip39-compatible-wallet-explained