Please note that randint is an obsolete function in the Matlab. You can use randi instead.
randint generates the matrix of uniformly distributed random integers. e.g.
generates M-by-N matrix of random binary numbers, i.e., 0 and 1 occur with equal probability.
Your example is similar to
out = randint(M,N,[IRANGE(1), IRANGE(2)]]);
where an M-by-N matrix is generated and the elements of the matrix will be in the range mentioned in the square brackets.
will generate a 1-by-1 matrix or just a number within the range [1, n], where n can be any integer.