Metaconginiton or as the author calls it, "thinking about thinking" sounds like intelligence to me

It's usually used to refer to something more akin to self-awareness than raw horsepower. Noticing that you didn't understand a paragraph that you just read is something that some people have to learn later in life than others, for example. It may have to do with intelligence, but also probably motivation and cognitive skills.

Edit: fixed typo I may have -> It may have