It means it’s not an easy book to read, maybe because the language used in the book is complex or the ideas are hard to understand.

Hi Cemre <3 "Hard read" pretty much means that it is difficult to read either because it is difficult to interpret (when a book uses a lot of symbolism), or simply because the vocabulary being used is advanced and uncommon in everyday language. Seriously congratulations on understanding a book so well that most people find difficult to get through. <3

What everyone else said! I think that War and Peace is a tedious read personally. By "tedious read," I mean that I think that War and Peace is a tedious book. It's way too long.

Hard means difficult. Hard read means something that is difficult to read.

Difficult, almost impenetrable (like a hard surface)