which covers basically all the fundamentals to be proficient in functional programming that has definitions that are opaque and unapproachable. And all of those have very simple examples, both in real life and especially programming. But definition has to come first, or you have this great mass of people that do not understand what they talking about even when they blog about it.
If you can take your time to understand that a type constructor (and take the time to see what it is) and a map function form a pair called functor, you are equipped to learn about monads.
It's not rocket science, but yes, it requires a bit of studying and learning, which is what people don't want to hear, and instead choose the long road of contrived example-driven, inaccurate and confusing blog posts.