I'm terrible at explaining stuff, but I guess a few terms, I can explain in general.
The command prompt used to be the only sensible means of operating a computer whatsoever. It's still "there," though most users would find it far too inconvenient to use. It's still accessible on just about any regular operating system through various means and in some instances, it can still be an extremely powerful tool provided ya know whatcha doin'.
Soundcards are additional hardware components. They can improve sound quality, but usually, PCs come with pre-installed soundchips installed that provide sufficient sound quality for regular listeners.
RAM means "random access memory." As you know, data you save in files is stored on your hard drive (or a different medium). But what about data you see on your screen, stuff you haven't saved yet? For example, at the moment of writing this, the entirety of my post has to be stored somewhere, and that's where the RAM comes into play. Without RAM, your computer would not be able to work at all. Think of it as a kind of short-term memory; you load everything into active memory that you know on the subject to do whatever it is you wish to do, right? It's similar with RAM. (that explanation might need some work)
RAM size is defined in bytes -- these days, it's normal for there to be RAM in sizes beyond Gigabytes, which woulda been enourmous about 10-15 years ago.
The CPU is the Central Processing Unit. It's another part without which you could do not a thing. The reason a computer is called a computer is because it
constantly calculates things; without calculations, nothing could be accomplished. The faster a CPU is, the faster your machine,
generally speaking. CPU speed is defined in Hertz, indicating the number of operations per second.
A GPU is a graphical processing unit, usually found as part of a graphics card. A graphics card is usually a combination of a seperate set of CPU and RAM that's more or less there to do the graphics calculating (which with modern games gets
very heavy in terms of workload). If you left that to the regular CPU and RAM of the PC, things would get ridiculously slow in any other aspect, hence why you need a GPU.
If you are unable to read the GPU specs, or any other of your PC specs for some reason or another, there's a tool called
Speccy that is capable of reading all your specs in detail.
… hope that helped at all. D: