"How is your day?"
Translation:Habari za leo?
Ya indicates that habari is singular and za indicates that it's plural. Since "news" and "information" are uncountable in English, that doesn't make a lot of intuitive sense from an English point of view, but habari can be either ("piece of information/news", "pieces of information/news"). In practice though, you generally say habari za ... but habari yako is much more common than habari zako.