What is Ethernet and how do I set it up with my computer?

Before you read any of this, keep in mind that I'm VERY technologically declined and I know very little about computers (especially given that I'm 18). So I recently acquired my own computer (an HP Pavilion 500 PC (whatever that means to you)) and I have just about everything for it configured with Windows... show more Before you read any of this, keep in mind that I'm VERY technologically declined and I know very little about computers (especially given that I'm 18). So I recently acquired my own computer (an HP Pavilion 500 PC (whatever that means to you)) and I have just about everything for it configured with Windows 10.
My only problem arrived when I realized everything involving internet was really, really slow. I was really confused because it was going off of the same wifi that our computer in the basement is still on, which runs much quicker, mind you (and also uses Windows 10). My computer had a ping of about 280 on average. But then I realized that the computer downstairs was hooked up to a lot of fancy things that mine isn't (which is only the outlet and the monitor). And I realized something it had was Ethernet, which is why when I selected the wifi on that computer it showed a monitor icon with a small cable, instead of just the standard wifi bars of all the other options. And considering the computer downstairs is used by the whole family, I can't just take it's things and use it for my computer. So now all I want to know is: What is an Ethernet cable? What do I hook it up to? Do I have to buy it? And if so, how much, from where, and what else do I need? I can't find anything online that puts it in terms that suits my lack of understanding for computers.

Any help is greatly appreciated!
Sincerely, your local technologically declined fool
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