I've learned to add comments to my code - from what I see commenting code is frowned upon by a certain subset of developers but I've taught myself that whenever I am doing something subtle or unintuitive to add a short comment explaining what the code is doing, for every potentially unnecessary comment I've added I've also saved myself time when I've had to come back to something months or years later and been able to refer back to the comment.
I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a... belief.
sum = sum_two_numbers(number1, number2)
Probably doesn't need a comment.
The other argument is that comments need to be maintained and are subject to decay. E.g. the code they are commenting on changes.
The book goes into other examples but i think the idea isn't to eliminate comments but to be thoughtful and judicious in which you use