A city in Ukraine.
The word 'sumy' is just the name of a place, like 'New York' or 'London'.
Examples:
Sumy is a city in Ukraine.
I want to visit Sumy someday.
People in Sumy are very nice.
I heard Sumy is a beautiful city.
In Sumy, there are many parks and buildings.
My friend lives in Sumy.