I would see it as a preface, or a table of contents, alerting the reader to what the book is about.

我倾向于把这看作一则前言，或一则目录表，用来警醒读者们真正理解这一文本。

youdao

Daniel: you can write anything about your book-what the book is about, what you think of it and so on.

丹尼尔：你可以写这本书的任何方面——这本书关于什么，你认为这本书怎么样，等等。

youdao

What is the use of a book about interior design without a plenitude of pictures in colour?

如果没有大量的彩色图片，一本有关室内设计的书还有什么用呢？

《柯林斯英汉双解大词典》

Note that in the opening pages of the book, Aristotle doesn't say anything yet about what kind of city or regime is best.

注意在书一开始的前几页，亚里士多德并未谈到,任何有关最佳城市或政体的言论。

耶鲁公开课 - 政治哲学导论课程节选

And so it appears, the three conversations end, Book I ends with uncertainty about what justice is.

而这显露出在三段会话结束时，在第一册结束时,正义仍是无法确定的概念。

耶鲁公开课 - 政治哲学导论课程节选

Now the first the eat food: well he has a long discussion, and as you'll know from the book, about what is food?

他做了大篇幅关于饮食的讨论,你可以从书中了解到,什么是食物

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

In essence, that's what the book is about.

ECONOMIST: The man and his pen

Although parts of IBM implement some of what the book is talking about, much of IBM is firmly entrenched in management practices aimed at extracting money from customers.

FORBES: The New Management Paradigm & John Mackey's Whole Foods

What is important about the book is that it helps spread the truth about investing to the masses in an easy-to-read manner.

FORBES: Seeking Alpha and Discovering the Truth