Native speakers may be surprised to see displays such as “Staff of the month“. In Standard English, this is “Employee of the Month“, since “staff” refers to all the workers.
“Staff” is a collective countable noun that refers to the people who work in an organisation:
1. “The staff were very good.”
“Staff” as a plural noun refers to the people who are part of a particular staff:
2. “10 staff were allocated to the task.” [Note: It is “staff” and not “staffS“].
While it is countable, it is much more commonly encountered in the singular, although the plural is NOT impossible:
3. Who is actually doing the taping is not publicly known, he says, despite reports that the STAFFS of BOTH the Prince (of Wales) and the Princess set up counter-intelligence units. [US press Report]
The word “staffS” here means “both the Prince’s staff and the Princess’s staff.” It is quite similar to “audience“, in this respect: invariably “audience” a singular noun; the exception is, when the reference is to more than “one group of audiences” (=not one group but groups of people collectively, not in one spot but in several places of concerts,movies or performances.)
In Singapore English, “staff” is often, if not usually, used to refer to ONE person (=synonymous with “employee).
This is wrong, of course.
Source: pgs. 210-211, Singapore English in a Nutshell by Adam Brown; standard English Dictionaries.