Well a unit rate is a rate with 1 as the denominator. So if you have a rate such as 4m per 2hrs then in order to make it a unit rate you change the denominator to 1. What ever you do to the bottom must be done to the top so to get 2hrs to 1hr you divide 2hr by 2, doing the same to the top you divide 4m by 2 and get 2. So you unit rate is 2m per 1hr. Rate= 4m per 2hrs and Unit rate= 2m per 1hr
I now it might be confusing just ask a question if you have one.
Hope this helps.