This is the 17604th most frequent Russian word.
турку
"Турку" is the name of the city Turku in Finland.
Here, 'Турку' refers to the Finnish city Turku as the destination of travel, being a geographic proper noun in the accusative case as it is the target of the action.
Я отправился в Турку на прошлой неделе.
I traveled to Turku last week.
In this sentence, 'Турку' serves to denote the proper noun for the city, used in the nominative case to function as the subject of the sentence.
Турку является старинным городом Финляндии.
Turku is an ancient city in Finland.
Here, 'Турку' represents the destination city, used in the dative case to indicate the direction 'to' as implied by the preposition 'к' (to/towards).