Refers to someone in a higher position at work or in an organization. Neutral term, but can carry a nuance of hierarchical distance.
新しい上役はとても厳しい。
My new boss is very strict.
上役に報告書を提出した。
I submitted the report to my superior.
Compound of 上 (うわ, 'upper') and 役 (やく, 'role, position'). The reading うわ is a rendaku form of うえ.