Many thousands of people began mining and then started buying big rigs with graphics cards and all sorts of things to scale their mining operations. One pc will most likely not have the computing power to mine anything as you will be competing with these mining farms. So if you want to mine for profit you must invest into more than just one standard PC
The previous poster is saying if you spend $10 a month on electricity running mining on your computer you will get less than $10 in cryptocurrency so you may as well buy $10 of which coin you want to mine rather and save your computer from burning power.
When mining your computer will get hot and run at full speed. (If you live in a cold place maybe this is ideal and you can heat your home to offset the money spent on electricity. )
Good luck learning more.