headcount

The act of counting how many people are present in a group.

The number of people present in a group or employed by a company.

More generally, a consideration of a company's appropriate staffing level based on some larger context. (Generally used adjectivally.)

“Due to economic difficulties, the company will be making headcount adjustments.”

By extension, one slot in a workgroup, filled or to be filled by one person.

“I've convinced management to give us one more headcount, to take some work off the rest of us.”