This is the 12959th most frequent Turkish word.
kalesini
"His/her/its castle" or "his/her/its fortress" in English.
In this sentence, 'kalesini' refers to 'his/her goal' in the possessive form.
Futbolcu, kalesini dikkatle savundu.
The football player carefully defended his goal.
Here, 'kalesini' refers to 'its castle', denoting possession.
Şehir, kalesini dağın zirvesine inşa etti.
The city built its castle on the mountain's peak.
In this context, 'kalesini' pertains to 'her castle', expressing ownership.