This error means that the script you are running is unable to connect to the mysql database. This could be for one of several reasons:

1. You did not specify the mysql database OR mysql user within your script.

2. You did not give the specified mysql user permission to access the specified database.

3. You did not create the mysql user within cpanel.

4. You did not create the mysql database within cpanel.

5. The password for your specified mysql user is incorrect within your script configuration.