This is the 340th most frequent Croatian word.
najboljih
"Najboljih" means "the best" (genitive plural form).
The word 'najboljih' is used here as the genitive plural form of the adjective 'najbolji', modifying 'prijatelja' (friends), indicating possession or association.
On je jedan od mojih najboljih prijatelja.
He is one of my best friends.
In this sentence, 'najboljih' is a genitive plural adjective form modifying 'pjesama' (songs), describing their quality as the best.
Ovo je lista najboljih pjesama ove godine.
This is a list of this year's best songs.
Here, 'najboljih' modifies 'priča' (stories) in the genitive plural, signifying that the mentioned stories are considered the best.