Array and database are two different things but they work together.
-- Arrays allow you to store a number of variables ( any ), and conveniently access them via one variable, so that you can iterate through them, organize them, sort them. Database holds a lot more power, and creates relationships between data, and allows very powerful queries with complex requirements.
If you query a database, you will likely get the results in an array, that's how it works most of the time.
In playmaker, Array and database is not supported currently, that's why I create ArrayMaker, to support working with arrays within playmaker, and for database, monosqlite ( available on the asset store) has a solution that works with playmaker.
Now, for an RPG, array and database will definitely help you, but first you need to really understand and grasp the concept behing database and arrays in order to use them in any kind of projects, not just RPG.