Brush up on !!!

JeffDo you have a driver's license ?
MikeNo. I am going to take the test in a couple of weeks .
JeffDidn't you drive in your country ?
MikeYes, but I have to brush up on my driving.
JeffAnd. You have to study the traffic rules too !
MikeYes, there is a lot of new things I must learn.
Explanation :
If you brush up something or brush up on it, you practise it or improve your knowledge of it.
Example :
Eleanor spent much of the summer brushing up on her driving.