np.c_ meaning code example

Example 1: np.c_ python

np.c_[np.array([1,2,3]), np.array([4,5,6])]

returns

array([[1, 4],
       [2, 5],
       [3, 6]])

Example 2: what is np.c_

>>> np.c_[np.array([1,2,3]), np.array([4,5,6])]
array([[1, 4],
       [2, 5],
       [3, 6]])
>>> np.c_[np.array([[1,2,3]]), 0, 0, np.array([[4,5,6]])]
array([[1, 2, 3, ..., 4, 5, 6]])