An echelon in an organization or society is a level or rank in it.
例句
...the lower echelons of society.社會等級較低的階層
N-COUNT
（士兵、車輛、軍艦、飛機等的）梯形編隊,梯隊
An echelon is a military formation in which soldiers, vehicles, ships, or aircraft follow each other but are spaced out sideways so that they can see ahead.