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

# Single element
print(matrix[0, 1])  # 2 - row 0, column 1

# Entire row
print(matrix[1, :])  # [4 5 6] - row 1, all columns

# Entire column
print(matrix[:, 2])  # [3 6] - all rows, column 2