This is the 769th most frequent Polish word.
ukraina
"Ukraina" in Polish means "Ukraine," the country in Eastern Europe.
Here, 'Ukraina' is being used as the subject noun representing the country of Ukraine.
Ukraina jest pięknym krajem.
Ukraine is a beautiful country.
In this sentence, 'Ukrainie' is the locative case form of 'Ukraina,' indicating the location of the action.
Podróżowałem po Ukrainie latem.
I traveled across Ukraine in the summer.
'Ukrainy' here is the genitive case form of 'Ukraina,' used to specify possession or association with the history.