In SAS, arrays provide a convenient way to refer to other variables via an index-able alias. This is convenient when you want to do the same operation on multiple variables in a data set. Having an index-able alias or short-cut to the variables means that you can put the operation in a DO loop that iterates over some index (do i=1 to 10...). When operating on the array, you are really operating on the variables that the array points to. 

Knowing how to program with arrays is an essential skill, so watch this video.