This is the 4383rd most frequent Polish word.
horrorów
"Horrorów" means "horror movies" or "horrors" in English.
In this sentence, "horrorów" refers specifically to horror movies, and it is in the genitive plural form, as it's governed by the negated verb "ogładać (to watch)".
Nie lubię oglądać horrorów w nocy.
I don't like watching horror movies at night.
Here, "horrorów" is used to describe a category in literature, specifically the genre of horror, also in a genitive plural form due to the preposition "z (from)".
Mam kolekcję książek z gatunku horrorów.
I have a collection of books in the horror genre.
In this use, "horrorów" refers to fans of the genre generally, also appearing in the genitive plural form associated with the possessive construct.