Stop explaining monads. There are two ways to approach them. One is by doing. The other is by math. If you can't understand how "monads are monoids in the category of endofunctors", you should try learning by doing.

Don't try reading about it, don't try reasoning about it. Just do it.

EDIT: okay, I'll explain. Haskell et al. have this really neat propensity to abstract well. That means that very many concepts (Promises, null types, etc.) can actually be abstracted into one concept (the Monad) because they all have the same behavior except for a couple of points. You won't believe me, but that's exactly it.

To explain "what monads are" you must explain everything (or most things) that monads can do. Save yourself the time. Don't read or write such a thing. They're so general and so abstract as to be totally meaningless without understanding what they're built on (either in the PL/doing direction or in the mathematical/conceptual direction).