"They need a lot of staff."

Translation: De behöver mycket personal.

[JeskeH]

why is många not correct? Has it got to do with coutable/incountable?

[Zmrzlina]

Yes. Personal is uncountable in this sentence, thus requiring mycket rather than många.

It can however be used as a countable if you really want or need to, but that's primarily something you have to know if working in human resources management or something like that. :p

[alexbfree]

'Personal' doesn’t have a plural 'personaler' then?