This is the 13319th most frequent Russian word.
мультимедийном
"Мультимедийном" means "multimedia" (adjective, related to using multiple forms of media).
The word 'мультимедийном' is used here as an adjective describing the mode of operation for the application.
Это приложение работает в мультимедийном режиме.
This application operates in multimedia mode.
The word 'мультимедийном' is employed to describe the nature of the classroom as equipped for multimedia teaching methods.
Она наслаждается учебой в мультимедийном классе.
She enjoys studying in the multimedia classroom.
Here, 'мультимедийном' qualifies 'центре', indicating that the center specializes in multimedia-related activities.