Okay, I understand. And I'm happy to tell you that 'personel' also refers to a group of workers :) Even if it's singular, that's still for a group. (the word 'group' itself is singular in Polish)
I guess you could say "członek personelu" to denote "member of the staff", but "pracownik" (worker, employee) would sound a lot more natural.
I understand - thank you. By the way, in modern spoken English, groups seem to float between being singular and plural, so you can say "England is out of the competition" but more commonly, "England are out of the competition", even though that would have been considered wrong a few decades ago.
I always hear this as "England is out of the competition = The team that is England is out of the competition" and "England are out of the competition = the people of England as a nation collectively are out of the competition" but you're right I hear them both equally and i don't think I've ever heard "England has/have won the competition"!
Staff is a collective singular noun, as is for example, a "herd" of cows. It is incorrect, strictly, to say "the staff are.helpful". But people often treat "the staff" as if it was a plural.
There is an interesting discussion here: www.onestopenglish.com/grammar/grammar-reference/american-english-vs-british-english/differences-in-american-and-british-english-grammar-article/152820.article. Jellei does have a point.
To add to the singular vs plural use of staff - this sentence is more likely to be understood by an English speaker as something said to a wizard/shepherd - 'is this your staff?'