You will need to review the course and retake a new final exam until you score 70% (18 out of 25) and pass.
According to California DMV requirements, you will have 2 consecutive attempts to pass the final exam.
In the unlikely event that you don't pass on both attempts, your account will be deactivated and you will need to re-register for the course again. This is done in accordance with DMV rules.
At Best Online Traffic School, you can retake the course for free and pay only after you pass.