Translation:The staff works in the White House.
You can infer from "werkt" that personeel is singular. In English, however, "the staff" almost always refers to several persons and so when referring to one person it would be more usual to elaborate and say something like "the member of staff", "the staff member" or even "the worker" or "the employee".
The Dutch sentence is referring to the staff, not to a single staff member. For collective nouns, singular is normally (always?) used in Dutch, in English it depends on the dialect:
- de brandweer blust de brand = the fire brigade put/puts out the fire
- de klas kreeg onverwacht een proefwerk = the class was/were given an unexpected test (group of students)
I think you'll find the singular is more common than the plural in Aus English. Usually, we're closer to the Brits, but not in this one...
But it depends on context too. If the collective is acting as one, then it's singular. If the collective is acting as individuals, then you use the plural.
The staff was about to mutiny.
The staff were going their separate ways.