Greetings!
A historical context in a book, is a context that refers to religious, economic, social, and political conditions.
Basically, it helps us to understand why people did what they did, what the consequences were, and what we can do to avoid making the same mistakes they did. Of course this would be referring to the past (history) not the present.
It can also help us to realize what motivated people to act the way they did years, decades, centuries (ago), etc.
Hope this helps!
