This is the 7848th most frequent Russian word.
калине
"Калине" is the dative or prepositional case of "калина," which means "viburnum," a type of flowering plant or its berries.
Here 'калине' is a dative case form of the word 'калина' (viburnum). It specifies the locus in this context.
На калине выросли яркие гроздья ягод.
Bright clusters of berries grew on the viburnum.
In this sentence, 'калине' is used to imply involvement or location within the plant, viburnum.
В калине живёт добрый дух леса.
A kind forest spirit lives in the viburnum.
This use of the word refers to the subject of the songs. 'Калина' (viburnum) is used in the accusative case as the focus of an action (singing about it).