the act of counting how many people are present in a place

The teacher did a quick headcount before we all got back on the bus. 在我们回公共汽车之前，老师清点了一下人数。

the number of people who are in a place, at an event, or employed by a company

Times were hard, and the company was unwilling to increase the headcount (= employ more people). 艰难时期，公司不愿意增加雇员。