You need to feel prepared and confident for your viva.
What does that mean for you? I don’t know.
I can make some guesses:
- You might feel you need to read your thesis a lot, so it sticks in your mind.
- You might need to know about your examiners, to feel happy with who they are and what (you think) they might ask.
- You might need to make a lot of notes, read a lot of papers or have a mock viva.
- You might need to read the regulations or you might simply need to ask a few friends about their vivas.
You will need particular things to feel prepared and confident for your viva. You are the only person who can figure out what practical things will help you feel that way.