It explains some limitations of IQ tests, and how it is the best predictor of success in a wide variety of areas.
For example, the USA military cannot make use of recruits with IQ below 80. they are unable to do anything productive, and get in the way of everyone else. It makes me wonder how they find a place anywhere else.
People are scared of IQ tests, and do not like to talk about them. there is pressure not to use them. For example, colleges might use them to identify students with the potential to do well in college, even though their records may have shortcomings. But racial politics have caused colleges to reduce their use of standardized tests.