This is the 378th most frequent Croatian word.
mladih
"Of the young" or "young (plural, genitive case)".
In this sentence, 'mladih' is used as a plural genitive form of 'mladi', referring to a group of young people and indicating possession or association.
Druženje mladih je bilo vrlo zabavno.
The gathering of the young was very enjoyable.
Here, 'mladih' is serving as an adjective modifying the implied noun for a group, describing their characteristic as young.
Vidjeli smo grupu mladih kako razgovaraju.
We saw a group of young people talking.
In this context, 'mladi' is used in its plural nominative form as a noun, representing young individuals collectively.