A hash (hash code/digest/message digest) is an encrypted form of a data. A hash of the password is generated and stored in your database.
In PHP hashes are generated using the PASSWORD() [41 byte] , md5() [128-bit (32 hexadecimal characters)] and sha1 [160-bit (40 hexadecimal characters)] functions.
You need to know which function was used for hashing the password before it was stored (you can identify this from the word press source code for creating a user account)
Then you need to know mysql or php wherein you write code to decrypt this hashed password to its original characters.