Niche

I've been learning about niches. My brother asked me if I had my own niche. I was confused because I didn't know what he was talking about. So I asked him what it was. He answered back, "it's something that you can do for money." As far as I remember, and I said, oh I haven't got one yet. Or so I do, but I didn't tell him anything yet. So I decided to search for my favorite niches. And some of these niches are hard to do and work on. So here are some niches I am interested in doing:

1. Reading online books, affiliate books for money, from clickbank marketplace, from Kindle, and physical books.
2. Writing skills, topics, titles, books, scripts, novels, a new language, foreign languages, other
3. Affiliate Marketing.

The goal in mind is to learn new things and to connect to many people that are interested in the same thing as mine.