There are many descriptions of the Leshy's appearance, but most indicate the presence of blue skin, green beard and large eyes popping out of their sockets. It is able to shapechange, and thus it's size can differ.
A very mischievous spirit, the Leshy gets it's enjoyment out of confusing travelers by magically altering paths, making trees seem to shift and generally leading his victims deep into the woods. It is said that a Leshy can only be thwarted by wearing one's clothes backwards and one's shoes on the wrong feet. This would confuse the Leshy itself, as it wouldn't know what way you were trying to travel in the first place.