used to describe an employee who deals directly with customers or physically makes a product 第一线（员工）◆Front-line staff should know all the products on sale. 第一线员工应该了解所有的销售产品。
used to describe a manager who deals directly with a group of workers （管理者）第一线◆The frontline manager has an important role in supporting the team. 第一线管理者在支持团队工作方面起重要作用。