This is the 1152nd most frequent Turkish word.
köyü
"The village."
The word 'köyü' is used in the accusative case, referring to the direct object 'the village' in the sentence.
Köyü ziyarete gittik.
We went to visit the village.
Here, 'köyü' again is in the accusative case, linked as the object of the verb, describing 'the village' modified by the relative clause.
Onun doğduğu köyü gördük.
We saw the village where he/she was born.
In this case, 'köyü' is in the possessive form, indicating ownership, meaning 'your father's village.'