The manager or chief of a section (kakari) within a company or government office; the person responsible for overseeing that department.
田中さんは営業課の課長です。
Mr. Tanaka is the section manager of sales.
課長に報告書を提出してください。
Please submit the report to the section chief.
会議で課長がプロジェクトの進捗を説明した。
At the meeting, the section manager explained the project's progress.