We can't see what
counts looks like, but from the code you posted we can assume that you have a 2D array, also known as multi-dimensional array.
A multi-dimensional array has multiple dimensions or layers if you prefer.
Every time you use a
, where 0 can be any valid number, you are stripping off one of the layers, so if you do
 you are going two layers deep.
What's happening in this example is that you are trying to count letters.
Every letter has it's own place inside the outtermost layer of this multi-layer array. The letter itself is stored on position 0 (that's why you see
), and the count is stored on position 1.
Hope that helps!