This is the 9144th most frequent Russian word.
северная
Northern.
Here, "северная" is used as an adjective describing the side of the house in relation to its position toward the north.
Северная сторона дома всегда холодная.
The northern side of the house is always cold.
In this sentence, "северная" is part of a phrase "северной части," indicating the northern region or area of Russia.
Архангельск расположен в северной части России.
Arkhangelsk is located in the northern part of Russia.
"Северная" modifies "звезда" to describe the star that is associated with the northern celestial direction.