This is the 18283rd most frequent Russian word.
шее
"Шее" is the dative case of "шея," meaning "neck" in English.
The word "шее" refers to the girl's neck as a location where the necklace is hanging.
На шее девушки висело красивое ожерелье.
A beautiful necklace was hanging on the girl's neck.
The word "шее" is used to indicate the part of the body (neck) where the mark is seen.
У него след на шее от шарфа.
He has a mark on his neck from the scarf.
Here, "шее" specifies the neck as the part of the body where the tattoo is located, emphasizing its visibility.