Here's how it works:

1. Your input text is hashed using SHA256, producing a 256-bit (32-byte) hash
2. The hash is converted to binary, giving us 256 bits
3. These bits are split into 24 chunks of 11 bits each
4. Each 11-bit chunk represents a number between 0-2047
5. These numbers map to words in the BIP39 wordlist