Bip39. Although you'll find BIP39 wordlists in languages aside from English, it is actually strongly not suggested to implement non-English words for wallet backups. It would make restoring the wallet difficult or unattainable. tell your wallet how to find your coins guiding it with the tree and are explained in https://bookmarkbooth.com/story19075667/bip39-wallets-https-linktr-ee-bip39-a-review-of-bip39-generator