How to learn the SaaS business?

Learn by doing. It's the most efficient way.

Some articles I've found useful:

• https://stripe.com/en-NO/atlas/guides/business-of-saas and https://stripe.com/en-NO/atlas/guides/saas-pricing
• https://canny.io/blog/saas-startup-ramen-profitability/, https://canny.io/blog/saas-pricing-lessons/ and all the other Canny blog articles
• https://tylertringas.com/micro-saas-ebook/
• https://www.sqreen.com/checklists/saas-cto-security-checklist

Lurk here on IH, read the discussions, start to get a sense of the challenges indie hackers are having. Then start generating some ideas and plans.

It won't happen overnight. Take your time to read, learn and then implement some steps little by little.

Don't waste your time for reading and lurking.
Find an appealing idea and think of how you would turn it into the business.
Ask questions, find answers, create a rough plan, add details, split into tasks, do them and see what happens.

This book is a pretty good start: Starting and sustaining.

The interviews are a great place to start. I love to learn from the people who have done it already. You can also check the products listed on IH and read about them.

But the biggest learning comes from engaging with the community, which is why I read and answer questions like this. Feel free to ask others. We are a very helpful community of people.