That's an extruded plane is all, with subdivision surface modifier, and it's just sitting on that. If you want to learn Blender, do these first: [link] They are around 5-6 minutes each, and if you ignore them, forget about using Blender
No problem! I have seen beginners not want to admit they are beginners and skip the basics and try to do things that are really complicated. 3 years later, they still have no idea what they are doing. Basics first, always