Judging by the reviews on Amazon, this book is really an introductory computer science text (which happens to use Python), not a "Python book". Just about any decent intro-CS or algorithms book will teach you about hash tables, since they're one of the most ancient (1953) and fundamental data structures of computer science.

If you already have a CS background and want to learn Python as an additional language, this book would probably be boringly redundant. You'd want a book that just said "Python dictionaries are implemented as hash tables" and assumed that you knew what that meant (e.g., the Python equivalent of the K&R C book).

On the other hand, if you were new to CS (and were willing to put in a lot of work), this book could teach you CS and Python at the same time. Just don't expect to get through it in a couple of weeks.