"how is work sister?"
Translation:habari za kazi dada?
Nope. Dada does not mean father any more than baba (the correct word for father) means baby. But it's an easy mistake.
Ya is the singular and za is the plural so I think it is plural because the question is How is work? instead of How was work? Work is an ongoing thing so using "is" refers to all of it versus "was" which refers to just one day.