Your examiners’ job is to examine you. (well, of course!)
But to do that they have to be experienced, they have to read your thesis carefully and they have to think a lot. While most of the questions in the viva will be aimed towards you, there’s no rule that says you can’t ask questions too.
So ask what they think. Ask what they would do next. Ask about publications and funding and monographs and anything else that you really want to talk about and get help with.
The first step is to think about what questions you would like to ask if you had the chance. Prioritise them and write them down on an index card for the viva.
The prompt can prompt you. (well, of course!)
It’s useful just in case you get so involved in answering the examiners’ questions in the viva that you forget there were things you wanted to ask too.