Weekly Tips: No.2
'Staff' and 'staffs': Which of these belongs in a company, and which will be helpful on a mountain trail?

We normally use "staff" to mean a group of people employed by an organization to do similar work. When used in this sense, it usually does not have a plural form; in other words, you cannot add "s". This seems strange. Since the staff is made up of many people, why is it not possible to say "staffs"? There is no answer to this question.

The staff in Japanese department stores are normally very helpful. (British English)
The staff in Japanese department stores is normally very helpful. (American English)

She employs a staff of ten.

If you want to talk about individuals who belong to the staff, you can say "a staff member/staff members", "one of the staff", "someone who is on the staff".

For a company to work efficiently, every staff member should feel that s/he is a valued employee.

"Staffs" is the plural form of "a staff" in the sense of a long stick used to help one when walking.

The road was steep and uneven, but luckily there was a good supply of staffs of different sizes. Even the tallest person in the group was able to find one that she could use.

Look up "staff" in an English-English dictionary to see its other uses, including the way it works as a verb. Then read this explanation, from the Centre for Independent Language Learning, Hong Kong Polytechnic University, and do the quiz that follows the explanation. (Note that this follows British English usage in allowing "staff" to take plural verbs [see "staff...are" above].)