This is the 18377th most frequent Russian word.
экспертном
"Экспертном" is the prepositional case form of "экспертный," meaning "expert" or "expert-related."
In this sentence, the word 'экспертном' is used as an adjective in the prepositional case describing the 'совет' (council) and specifies its nature to be related to expertise.
Он выступал на экспертном совете.
He spoke at the expert council.
Here, 'экспертном' describes 'уровне' (level), emphasizing the proficiency or specialized aspect of the level.
Мы обсудили эту проблему на экспертном уровне.
We discussed this issue at an expert level.
In this context, 'экспертного' describes 'подхода' (approach), highlighting its expert quality.