This is the 2131st most frequent Russian word.
автобусов
"Автобусов" means "of buses" (genitive plural form).
The word 'автобусов' is used in the genitive plural form to indicate quantity after 'много' (many).
Я видел много автобусов на улице.
I saw many buses on the street.
The word 'автобусов' is in the genitive plural form denoting possession or relation, meaning the 'times of arrival' belong to the buses.
В расписании указано время прибытия автобусов.
The schedule shows the arrival times of the buses.
The word 'автобусов' is in the genitive plural form as required by the negative construction 'ни одного' (not a single).