Most Minecraft plugins offer database storage such as SQLite, H2, or MySQL. Although SQLite and H2 are recommended as they are easier to migrate and simpler to use, MySQL can also be used if you have a web host (not recommended). To setup your MySQL database, simply login to the Multicraft control panel and go to "Advanced > MySQL Database" to create it. This is a local database that is accessible by external sources. It is not recommended to use databases from other services such as web hosting, etc for plugins as it may cause lag on your server.
Note: A single database will work for multiple plugins.
Default MySQL port is 3306.