All about the stock buybacks

I have kept up with the entirety of the Nijisanji saga since the beginning of this year, but there are one or two things I'm still curious about. One of those things is the stock buy backs.

So I came here to ask you guys about it. And yes, I came here to ask you guys about it because I asked Google first.... and I still don't get it. (If anyone could tell me what "shares" are, I would very much appreciate it)

I'd say that I'm quite financially illiterate so I know very little about these things. My own lazy ass made me not look up any of these things until now. All I know about buybacks are the things that I heard about it from one time comments on this sub. Like, I heard that they, supposedly, make the company look better for inverstors? Also, apparently, buybacks have a cooldown? You can't just spam them left and right? I would like to know if that's true.

I also heard from some comments on this sub that, thanks to these buybacks, Riku is wasting money that he cannot get back, which doesn't surprise me considering.... EVERYTHING THAT LED UP TO THIS POINT, but some more enlightenment on why that's the case would be very much appreciated.