This is the 13917th most frequent Swedish word.
östers
"Östers" is not a standard Swedish word. It could be a misspelling or part of a proper noun.
In this sentence, 'Östers' is used as a part of the compound word 'Östersjön', which refers to the Baltic Sea.
Jag gillar känslan av frihet vid Östersjöns strand.
I enjoy the feeling of freedom by the shore of the Baltic Sea.
Here, 'Östers' is again used in 'Östersjön', emphasizing the naming of the Baltic Sea in a context involving activity.
Simningen genom Östersjön var en stor utmaning.
The swimming through the Baltic Sea was a great challenge.
The word 'Östers' in 'Östersjöns' assigns genitive case to the compound, indicating possession or association.