Translation:Her brother does not want to have coffee either.
Broren hennes vil helst ikke ha kaffe.
'heller' and 'helst' are the comparative and superlative forms, respectively, of 'gjerne': gjerne - heller - helst
'gjerne' = 'happily/gladly', 'heller/helst'' both translate to 'rather', but only 'heller' translates to 'either' and 'helst' most often translates to 'preferably'.
Yes, but since heller and helst have a different meaning, why can't we use heller here?
I am assuming it is possible to both say jeg vil heller ha kaffe and jeg vil helst ha kaffe?
In Dutch and German it would also be possible to put both sentences in the negative. (e.g. ich möchte lieber nicht kaffe trinken) What would be the negative in Norwegian?
I've never really thought about it, but it's indeed rather strange.
Basically, 'heller ikke'/'ikke heller' has come to only mean 'neither' or 'not... either'. It does not work as a negative form of 'heller' in the way you'd expect it to. So to express that, you either have to use 'helst ikke', or rewrite the sentence to a positive one again:
"Jeg vil helst ikke ha kaffe."
"I'd rather not have coffee."
"Jeg har mest lyst på te."
"I would prefer some tea."
'Heller ikke' works in two settings; when your agreeing with with somebody else, like in the sentence we're currently discussing:
"Nei, ikke jeg heller."
"No, me neither."
And when there are two things you're expressing that same negativity towards:
"Drikker du kaffe?"
"Do you drink coffee?"
"Nei, og ikke te heller."
"No, and not tea either."
Which can also be expressed in this format:
"Nei, (jeg drikker) hverken kaffe eller te."
"No, (I drink) neither coffee nor tea."
Bare hyggelig, oulenz!
That sentence doesn't work in the same way. It would mean that you'd rather have no amount of coffee than have X, so it's not something you'll find yourself saying very often:
"Jeg vil heller ha ingen kaffe, enn dårlig kaffe"
"I would rather have no coffee, than bad coffee."
I'd sooner say 'jeg drikker heller...' (I'd rather drink...), but you get the idea. :)