This is the 6543rd most frequent Russian word.
danske
The word "danske" is not Russian; it appears to be Danish and means "Danish" in English.
'Датские' is used to describe the origin of the desserts, linking them to Denmark.
Мы попробовали датские десерты во время поездки.
We tried Danish desserts during the trip.
'датский' is used here as an adjective to describe the language being studied.
Я изучаю датский язык в университете.
I study Danish at the university.
'Датская' describes the type of architecture, representing something characteristic of Denmark.