This is the 17742nd most frequent Polish word.
zoologiczny
"Zoologiczny" means "zoological" in English.
Here, 'zoologicznego' describes the nature or domain (zoological) related to the subject matter (in this case, the theme of the book).
Książka na stole dotyczy tematu zoologicznego.
The book on the table pertains to a zoological subject.
In this sentence, 'zoologiczny' is used to describe the type of garden, i.e., one that is zoological and pertains to animals.
Odwiedziliśmy ogród zoologiczny w weekend.
We visited the zoological garden (zoo) over the weekend.
Here, 'zoologicznego' describes the type of store, specifically relating to animals and their supplies.