eg: 本书作者 （The author of this book ）

no , they misunderstood what you said ! “本书” means: this book ! "书" means all of books . eg: 本书作者 （The author for this book ）

本 is a measure word! Have you learned about these yet? You probably see 一个人 which means one person. The "个“ is a measure word. You have to use the appropriate measure word for each noun, so with 书 you can't use 个, you have to use 本。 Hope this helps!

a book = 一本书，a means 一，book means book, 本 has no meaning, but u must write in this way, just like a dog(一条狗) a pen(一支等) a hill(一座山) a peper（一张纸） a + 量词 + something. 量词 use in describ shap of this thing, just like 一条河，一条狗，一条虫， river dog worm, 条 some thing long shap 一座山 一座高楼 一座塔 一座城市，hill building towe city, they r all huge hm, some times u can use different 量词 to discribe one thing , like 一只狗 一条狗 both ok, but some times u can only use one 量词to discribe another thing like 山，一座山 only