If you look at the base directory where WordPress is installed (somewhere under /var/www/ is normal) you will find a file called wp-config.php
In here you will see a set of declarations for the database:
/** The name of the database for WordPress */
/** MySQL database username */
/** MySQL database password */
/** MySQL hostname */
/** Database Charset to use in creating database tables. */
/** The Database Collate type. Don't change this if in doubt. */
In your case the data should be filled with the info you need.
For questions such as these (i.e. internal to WordPress) may I suggest that https://en.forums.wordpress.com/
would be a better place to seek answers rather than this forum?