prob with a FM question!!

i came across this que in my FM module and it is an illustratio, the solution is given but m unale to understand the solution:

Q. Ramanuj has taken a 20 month car loan of rs. 600000. the rate of interest is 12 percent per annum. what will be the amount of monthly loan amortization?

Ans. A=600000/PVIFA=600000/18.0456=rs. 33,249.1

monthly interest = 12 percent/12=1 percent

m unable to understand the whole concept of pvifa in this. pls help!!