Unclear on the concept

Hello,

I installed this Wolfram Language plugin into my Intellij Idea IDE.  I use Mathematica a lot and have recently been executing Mathematica code through JLink and Kotlin.  So, I saw this plugin and installed it.  I also installed the Wolfram Language(script?) SDK.  Well ok now what? Do I write scripts with this like in Mathematica?  If so then how do I execute /run them?  Can I generate plots, and other graphics with this capability(?)?  Do the graphics pop up in a window?  Is this an equivalent to Mathematica, better than Mathematica, not as good as Mathematica, what?  

Thanks