So Explorer window, as you will see over here, is basically a file management system, this is where you'll open, close, build, and save your projects and graphs.
This is the main thing, this is the heart of Substance Designer, where all the magic is done, since this is where people construct their nodes, networks in order to produce complete materials, that's why we call it the heart of Substance Designer.
So if you want the node property, just double click on the nodes, if you want the whole graph property, you just double click in the empty area and it will give you the whole graph property.
Uniform color for the roughness will show here the roughness, if you double click the roughness directly or uniform here, basically it will show you that property here.
Because all of these panels are that I can literally remove, like suppose if I want to remove this one, I can just click it and I can put it wherever I want.