The viva is a discussion but as your work and capability is being assessed most of the questions will flow from your examiners. Their questions will prompt response and the discussion that follows.
You have the opportunity to ask questions though: if there are things you want to discuss, opinions you want to check or ideas you want to explore then take the time to ask.
In preparation for the viva take some time to think about what you might ask. What opinions would you really value? What aspects of your work do you want to talk about? And as this is a limited opportunity, which questions would you prioritise asking?