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

def zamiana(tab):

    array_to_return=[]
    for i in range(0, np.size(tab, 0)):
        new_array=[]
        for j in range (0, np.size(tab, 1)):
            new_array.extend([tab[i, np.size(tab, 1)-j-1]])
        array_to_return.append(new_array)
    return np.array(array_to_return)

print(zamiana(a))