Hashing basically means taking a password and distorting it in a certain way so that it's very hard to guess what the original password was.
For example, the MD5 hash of the password "PASSWORD" is "319f4d26e3c536b5dd871bb2c52e3178".
Often, passwords are stored in this "hashed" format. When a user tries to log in, whatever password they typed in is hashed in the same way and compared with the hashed version of the password stored in the database, and they're allowed in if the two hashes match.
The reason for doing this is if someone manages to see your database, they can only steal the hashes, not the original passwords, which is less useful to them because they can't actually use them to log in.
Anyway, all that aside, if you don't know where/how the passwords are stored, you need to find out from someone who does...there's not much we can do otherwise.