Question: You make monthly payments on your car loan. It has a quoted APR of 6.4% (monthly compounding). What percentage of the outstanding principal do you pay in interest each month?

I get it that the solution would simply be 6.4%/ 12= 0.5333%. But I still can't get my head around the idea. I'm quite confused with the word outstanding principal. Can someone give an example like having an actual number for the outstanding principal so I can visualise it better?