This is the 307th most frequent Swedish word.
östersund
Östersund: A city in central Sweden, located in the region of Jämtland.
Here, 'Östersund' is used as a proper noun denoting the name of a city in Sweden, serving as the object of the action of going.
Jag åkte till Östersund förra sommaren.
I went to Östersund last summer.
'Östersunds' is a possessive form indicating that the cheeses are associated with Östersund, a city.
Har du provat Östersunds berömda ostar?
Have you tried Östersund's famous cheeses?
In this context, 'Östersund' is mentioned as an identifying name of the city being described.