I'm no expert, but everything is relative. I'll try to explain in simple terms even I can understand.
This is your computer's operating system - the program that makes it work. You shouldn't have to worry about this because new computers come with Windows 8.1.
This is the actual machine inside the box that runs everything. The 'GHz' rating is the Clock Speed, or how fast the computer runs. The 'Intel Core2 Duo' and 'AMD Athlon' are the brand names of the two biggest companies making processors. The rest is the model number. As you can see they say that one level (4400) is required as the absolute minimum and another level (6600) is recommended. Of course the "recommended" costs more than the "required", and you can be sure that you will need the higher level to run any major mods.
This is the computer's memory storage. Any new computer is going to come with at least 500 GB and space to put in a backup drive which may hold as much as 3 TB. The '2 GB required / 4 GB recommended' is how much space you'll have to have free to store the game itself. This shouldn't be a problem.*
This is the machine that makes all the pretty graphics work. Having a separate dedicated card is better than having a built-in graphic system that the computer itself runs. Sometimes it's hard to tell from reading the descriptions, so it's always good to ask.
Same as the Video Card, but for sound. Again, having a separate card dedicated to running the audio is better than "onboard" sound run by the computer.
This is the program that runs the video. The higher the better. You should be okay, as new computers come with DirectX 10 (or maybe even better - I don't know what the latest greatest is).
This is the disc drive. Any new PC should have one this good or better.
If you don't know what those are you shouldn't be doing this.
To play SH5 you originally needed to be connected to the internet just to play the game. They dropped that after awhile, but you still need to be connected once to start the game the first time. Since we're talking on an internet forum, I assume you are connected.
* If you really don't know this, it's not important but it does help to understand.
1 Bit is the absolute minimum concept for computing. It's like a switch, and only knows to be on or off. It's commonly expressed as '0' and '1', which is why you sometimes see strings of ones and zeroes.
1 Byte is the basic function. It is made up of 8 Bits, so it can express eight zeroes or eight ones, or anything in between. This gives it 255 possible combinations. The computer knows this, so you don't have to. Every letter you type uses 1 byte.
1 Kilobyte (KB) is one thousand bytes. Actually it's 1024, because everything in the computer world doubles (1-2-4-8-16-32-64-128-256-512-1024 etc), but a thousand is much easier to remember.
A thousand Kilobytes (or one million bytes) is a Gigabyte (GB).
A thousand Gigabytes (One million Kilobytes or one billion** bytes) is a Terabyte (TB).
There are words for even more multiples, but a three-Terabyte drive is a lot, so we don't need to worry about that.
** If you're British you will call this a "thousand-million", with "billion" being reserved for the next level up.