This is the 1041st most frequent Polish word.
zakopanem
"Zakopanem" is the locative case of "Zakopane," referring to being in Zakopane, a town in Poland.
The word 'Zakopanem' is the instrumental case of 'Zakopane', a proper noun referring to a town in Poland, used here to express location after the preposition 'w' (in).
Spędziliśmy weekend w Zakopanem.
We spent the weekend in Zakopane.
In this sentence, 'Zakopanem' is similarly the instrumental case used after the preposition 'w' to indicate 'in Zakopane', specifying the location.
Widok gór w Zakopanem był zachwycający.
The view of the mountains in Zakopane was breathtaking.
The same case and usage of 'Zakopanem' occurs here to talk about the location someone has visited.