My laptop has 8Gb RAM and Intel i5 processor, and I can use a drawing program (Krita or CSP) fine while also having a browser and a few other apps open, although it lags at large canvas or brush sizes, and I sometimes get afraid of using too many layers or opening too many files at once in case it crashes lol (typically I can easily have a couple dozen layers though).
Agreeing that at least 8Gb of RAM is necessary - anything less will definitely be very restricting. Btw more RAM doesn't make the computer faster, but running out of RAM makes it either slow to a crawl or crash.
GPU is supposedly necessary for gaming, 3d modeling, and video editing, and may be helpful but isn't necessary for drawing (source: I don't have one)
SSD is a faster kind of hard drive. Loading/saving files and booting up the computer should be faster with one. The speed difference is supposed to be significant but idk since I've never used one.
As for processors, generally Intel i3 isn't good, i5 is decent, i7 is good, i9 is really high end. Not sure about AMD processors.
That's pretty much all I know