点人数
to count the number of people present somewhere
There look to be about 50 people here - I haven't counted heads yet. 看起来大概有50人在场——我还没有清点人数。
Teachers regularly count heads during a school trip.
Hold on - let me count heads before we make a reservation for a table.
When the fire alarm sounds, everyone goes to their appointed fire station and waits for someone to count heads.
They are counting heads to make sure they have at least 50 supporters in the room.
See also: count verb (NUMBER)