How to encode a password field using php

Answer 1

via encrypting.
Check "sha256", and then apply a "salt"

Answer 2

Please learn more about Encoding, Decoding, Encryption, and Decryption. They are different.
If you want to encrypt your password, I would recommended using password_hash($plain_password, password_default) and to verify password while login use password_verify($password_input)