Bitcoin mining is when a computer has all of its running power dedicated to "mining".
Now, mining doesn't really do anything as such, it is used as an example because the more people mine, the harder it is to get bitcoins, like real mining with precious ores.
This generates bitcoins that can be used to purchase services or things.
If your curious of how this could possibly make money, its really a matter of, why not?
If I put a 5 dollar note in front of you (I don't know if your american, but lets just use dollars for a placeholder) and I ask you how much it is worth, what would you say? Most likely, 5 dollars.
What makes that mix of linen, silk and cotton worth 5 dollars? Well, nothing really. Enough people accept it as being worth something that it has become worth something. Thats how most currency works since we left the gold and silver standard. Bitcoins are exactly the same, mining doesn't do anything worth making currency, but enough people say its a currency that it is a currency. Thats it.
To do bitcoin mining, you require getting a computer or device that you would completely dedicate to mining. Unfortunately though, most cheap things don't make back the electricity they cost to run, some people have invested in specific bitcoin mining machines that costed more than 20,000 dollars, and when they bought them, they were basically printing money, but unless you are willing to go all in, its not worth your time, and won't really make you anything.
If your looking to make money with computers research SEO (search engine optimization), companies are willing to pay up to the 5 digits if they can find a good SEO expert.
Good luck with your future endeavours.