The whole procedural Texturing is hella confusing ngl 😭😭😭
Keep going, and it will all click into place.
It all looks a bit intimidating when you start learning procedural texturing.
It is best to think of each node one by one, make use of the excellent Node Wrangler add-on. SHIFT+CTRL and click on a node to view the result of the selected node.
Try adding a material to the default cube, pick a node, any node, and add it to the material, use the viewer as above, and play around with the settings.
Here is a link to Blender.org - Shader Nodes for a list of all the nodes, clicking on them will give you a full explanation for each node.
Its a huge subject, far to much information to squeeze into a single course. If we tried, it would be even more confusing.
Procedural texturing is one section of road on your Blender journey, the road unfortunately is not straight and flat, there are inclines and declines, bends and turns in any direction.
Imagine riding a cycle along this road, some parts take more effort. With lots of perseverance you will make it over this hurdle.
You can always make a turn, and continue your journey, revisiting this section later.