This is the 18449th most frequent Russian word.
этнических
"Ethnic" or "relating to ethnicity."
The word "этнических" is used as an adjective modifying "традиций", indicating that the traditions are related to ethnicity.
Сохранение этнических традиций является важной частью культуры.
Preserving ethnic traditions is an important part of culture.
Here "этнических" describes "групп", indicating diverse groups based on ethnic backgrounds.
В этом городе проживает множество этнических групп.
Many ethnic groups reside in this city.
"Этнических" modifies "обычаев", showing the customs are characterized by specific ethnic associations.