Ok, I'll bite.... you didn't mention the motherboard (mobo) or the power supply (PSU), but the processor looks good. The video card... I would call mid-range, or decent. With video cards, well, those really depend on how much money you have to dump into them and how good you are at finding deals. 8 GB of RAM (the memory) should be fine for gaming. For the eight core processor I'm guessing the motherboard is good, and if your friend has a clue s/he got you a good power supply to go with it. Windows 7 64 bit is great for gaming. It's been out for a long time, is now very stable, and works great. I hear Windows 10 is getting good reviews, but you don't need to jump. Windows 7 is good.
You can put a little bit of money into a gaming computer... or a ridiculous amount. Some of it honestly just comes down to the money you have to throw at it, and if that addition is really worth it to you. For video cards, there's the low end, middle end, high end, and 'thowing away ridiculous amounts of money' category.
With your video card you probably won't run games on 'Ultra' but you can run them probably on medium, maybe high for some games (or 'low' if they're really graphics intensive games). Really the higher end video cards cost bucks, and then they need a higher wattage power supply and lots of cooling.
What you can do is do a web search for 'can i run it?' from the computer you want to run a game on and there's software that will scan your system and tell you if you can run certain games with your system and at what settings. Honestly, to me, a mouse I like and a keyboard I like, and headphones, are actually worth their cost in terms of value and game enjoyment. Those little things actually make gaming much more fun.
And then mostly people upgrade the video card first when they can't run a game. if you can't run witcher 3 or Fallout 4, I'm guessing it would be the video card, but you'll find that out. And the beauty of your own computer is you know the specs so you can always upgrade a part later if you want a better (aka more expensive one). So, don't worry how your system compares with everyone else out there. Relax and enjoy your new computer!
oh, and for terms and things, it depends on what you want to know. I'd ask your friend that got you the parts for an intro; that's probably the easiest. no need to overwhelm yourself. go have fun first.