I'm assuming you're asking for some ideas, or about how to think of them. I could give you a list of a thousand ideas but it doesn't really matter unless you're passionate about them.

Instead I would focus on an issue that you've experienced, perhaps something that you find annoying and can build a solution for. It's highly likely that someone else has the same problem as you and is willing to pay for a solution to it. You get two benefits, one is that it's something that you've experienced so you're probably passionate about building a solution for it, and second it's a problem that exists instead of creating a solution in chase of a problem.

This article gets posted a lot, but I think it's worth a good read.

http://paulgraham.com/startupideas.html

This blog post helped me a lot as well. It helped me get better as seeing problems and thinking of solutions to them:

https://jamesaltucher.com/blog/the-ultimate-guide-for-becomi...