This is the 754th most frequent Polish word.
gdyni
"Gdyni" is the locative case of "Gdynia," meaning "in Gdynia," a city in Poland.
Here, 'Gdyni' is the locative case form of the proper noun 'Gdynia' (a city in Poland), used to specify the location of an action.
Byłem w Gdyni na wakacjach.
I was in Gdynia on vacation.
In this example, 'Gdyni' again is in the locative case, indicating the place where the action is happening.
Spacerowałem ulicami Gdyni, podziwiając architekturę.
I walked through the streets of Gdynia, admiring the architecture.
Here, 'Gdyni' is in the genitive case, which often denotes possession or association; it describes 'history' as belonging or relating to 'Gdynia'.