This is the 8077th most frequent Polish word.
nikopolu
The word “nikopolu” does not appear to have a meaning in Polish; it may be a proper noun or misspelling.
In this sentence, 'Nikopolu' refers to the locative case of the proper noun Nikopol, a city name. The locative case is used after certain prepositions to specify location or place.
Mieszkałem w Nikopolu przez dwa lata.
I lived in Nikopol for two years.
Here, 'Nikopolu' is in the locative case, indicating the location where events occurred, referred to in the context of memories.
Wspomnienia z czasu w Nikopolu są dla mnie bardzo ważne.
Memories from the time in Nikopol are very significant for me.
In this usage, 'Nikopolu' is again in the locative case, utilized here to specify the topic or location concerning the conversation.