This is the 968th most frequent Hungarian word.
hova
"Where to?"
In this sentence, 'hova' is used as an interrogative pronoun asking for the destination of the action described by the verb.
Hova mész holnap reggel?
Where are you going tomorrow morning?
Here, 'hova' defines the destination or location where the book should be placed, used in a subordinate clause.
Nem tudom, hova kell tenni ezt a könyvet.
I don't know where to put this book.
In this instance, 'hova' is used within an indirect question, implying a destination to assist with completing an action.