"How is the evening?"
Translation:Habari za jioni?
You will hear both in Tanzania (and see them in this course). Habari is N/N class, so the singular and plural are indistinguishable. However, ya indicates singular and za plural. Both forms literally translate to 'news of the evening?'
However, if we use another meaning of the word habari (message) the difference becomes more obvious in English:
habari ya jioni?: message of the evening?
habari za jioni?: messages of the evening?
My understanding is that you would use za when you haven't met the other person for some time. That is: there is much news to tell. But, if you greet someone that you have seen the same morning you would use ya. Is this so in practice?
This would imply that you always say "Habari za siku nyingi". And indeed, I have never heard "Habari ya siku nyingi"