one's social standing; one's place; one's station in life
Often used scornfully to belittle someone's status or to say they are acting above their station. Common in phrases like 分際で and 分際のくせに.
あんな分際で生意気な口をきくな。
Don't talk so cheekily with your low standing.
自分の分際をわきまえなさい。
Know your place.
Compound of 分 (ぶん, 'part, share, social position') and 際 (さい, 'edge, occasion, time'). The combination came to mean one's allotted social standing, often with a belittling nuance.