C = mat2cell(A,[2 2],[3 2])
means that numeric matrix A is to be broken up into cells.
The first row of cells is to have [2 2][1] -> 2 rows. The second row of cells is to have [2 2][2] -> 2 rows. This is a total of sum([2 2]) = 4 rows, and it is an error if A does not have that many rows.
The first column of cells is to have [3 2][1] -> 3 columns. The second column of cells is to have [3 2][2] -> 2 columns. This is a total of sum([3 2]) = 5 columns, and it is an error if A does not have that many columns.
Thus, the sizes of the entries in C will be all combinations of [2 2] with [3 2], so
{size [2, 3], size [2, 2] -> leading 2 from the first 2 in [2 2]
size [2, 3], size [2, 2]} -> leading 2 from the second 2 in [2 2]