Stable means relatively difficult to break. Honestly it's difficult to define unless you have experienced something not so stable like an Arch base Linux. That shit will piss you off trying to get even the simplest of things to run.
Examples of Arch: We can see all your drives but you have to manually edit the Fstab file to get them to auto mount on startup. Package manager, what's that? Just use command line because everyone knows how to build packages from source. Another good example of stable and not stable might be x11 vs Wayland compositors. Wayland will often have screen tearing worse than a chainsaw victim at a crime scene.
Nope, as a beginner you want everything to work with a graphical user interface and you want it aesthetically pleasing.