Before you go and implement a database you should first understand what a database can help to achieve, this will ensure that you're not burning time unnecessarily deploying things you don't need.
What is a database used for
Databases are used for centralised storage with unrestricted limitations to read, write new data and modify existing data. Storing data in a database can also be efficient, decreases time for looking up data that you can export into another application / format without significant difficulty.
The most common time you'll want to interact with databases is when you're setting up a 'network' using tools such as 'Bungeecord' or 'Velocity'.