This is the 16382nd most frequent Polish word.
wagonów
"Wagonów" means "of wagons" or "of railway cars" (genitive plural form).
In this sentence, "wagonów" is used to denote the plural form of "wagon," referring to the railcars in a train at a railway station.
Na stacji kolejowej było wiele wagonów.
At the railway station, there were many carriages.
Here, "wagonów" indicates the genitive plural form of "wagon", signifying that the book's topic was related to carriages.
Książka była na temat zabytkowych wagonów.
The book was about historical carriages.
In this context, "wagonów" represents the plural form in genitive to indicate that several rail freight cars were utilized in the transportation process.