This is the 576th most frequent Serbian word.
млади
"Млади" means "young" or "youth" in English.
Here, 'млади' is a noun referring collectively to young people.
Млади су будућност нашег друштва.
The young are the future of our society.
In this sentence, 'млади' again functions as a noun referring to young individuals.
На тој слици су млади разног порекла.
In that picture, there are young people of various backgrounds.
Here, 'млади' is an adjective describing the subject 'уметник' (artist), meaning 'young'.