Q. what is "the nature of spirits, of the laws by which they are governed, and the signs by which they may be known"?

in the lds teachings of the prophets: joseph smith manual, in The gift of discerning of spirits allows the faithful to distinguish between the influence of good and evil spirits, joseph smith writes:

As we have noticed before, the great difficulty lies in the ignorance of the nature of spirits, of the laws by which they are governed, and the signs by which they may be known; if it requires the Spirit of God to know the things of God; and the spirit of the devil can only be unmasked through that medium...

Q. what is the nature of spirits, of the laws by which they are governed, and the signs by which they may be known?