What does Nan Yi mean? There is no integral.

You should be talking about the calculation of the Book of Changes, right? This is a statement specially used for divination "travel".

Nan Yi is beneficial to the south.

For example, "small livestock" are easy to be north, Nan Yi, southeast, southwest, northeast and northwest, or easy to be due to the west, and the rest are unfavorable, so it is not easy to be due to the east.

In other words, the person who occupies this divination is conducive to the development of the north and other directions, and is not conducive to the East, otherwise it is an obstacle.