This is the 17516th most frequent Russian word.
тракторов
"Tractors" (plural form).
Here, 'тракторов' is in the plural genitive case, showing the amount of tractors.
На поле работало пять тракторов.
There were five tractors working in the field.
In this context, 'тракторов' is used in the plural genitive case, indicating possession or a source of the noise.
Шум тракторов был слышен издалека.
The noise of the tractors could be heard from afar.
Here, 'тракторов' is used in the plural genitive case within an expression of quantity or type of event.