[9 [b c]] is a "function" that, when applied to a, firstly applies c to a. The result is taken to contain within it a formula (at address b) that is then applied to that result.
Here is the reduction:
*[a [9 [b c]]] =>
*[*[a c] [2 [[0 1] [0 b]]]] =>
*[*[*[a c] [0 1]] *[*[a c] [0 b]]] =>
*[*[a c] *[*[a c] [0 b]]]