Now, with Al's key on his keyring, Bill can send a message to Al. Bill e-mails this to Al, confident that no one but Al will be able to read it. PGP is smart enough to realize that the file is an encrypted message, and knows what to do with it. Since the message was encrypted using Al's public key, PGP needs Al's secret key to decrypt it. File is encrypted.
Secret key is required to read it.
You need a pass phrase to unlock your RSA secret key. Pass phrase is good. There is, but it'll have to wait until next month.