This is the 18376th most frequent Russian word.
экспертного
"Экспертного" means "expert" or "pertaining to an expert."
The word 'экспертного' is used as an adjective modifying 'совета', meaning 'expert' referring to a council made up of experts.
Мы получили отчет экспертного совета.
We received the report from the expert council.
The word 'экспертного' is used as an adjective describing the level associated with the group, implying its expertise.
Компания предложила создать экспертного уровня группу.
The company suggested creating an expert-level group.
Here 'экспертного' modifies 'мнения', indicating that the opinion comes from an expert.