I know it's not a literal translation of dishes but I would imagine this is like saying "are you washing up" with vyombo (in this context) meaning a general term for things that are washed in a sink. Is this right?
So basically what logically makes sense is Unafua right? Well that means "you bleed" for some reason. "You clean" is safi, as in "kusafisha" so "you are cleaning/washing the dishes" is "unaosha vyombo"
What is the difference between "cleaning" and "washing"? It said "cleaning" was wrong, but in English it is interchangeable with "washing". I think either should be accepted unless there is an important distinction between the two in Swahili that I am not familiar with.