the staff were
Today I've read this sentence "the staff were very helpful with information". I thought that uncountable nouns are always singular. Can anyone explain this?

Question

Answer

Staff, like the police and people, function as "they". Staff is not an uncountable noun, but instead represents a plural.

Answer

Staff is not an uncountable noun. Its a collective noun. A collective noun can be grammatically plural if you are talking about individuals in that group.

The staff were arguing amongst themselves. (as individuals)
The jury was unanimous.  (as a group)