Faunus is a character from Roman mythology who was said to be a god of forests and wild animals. He was often depicted with the body of a human and the legs of a goat, and was thought to be a mischievous and playful deity.
In modern times, the term "faunus" is sometimes used to refer to creatures that share some of these characteristics, such as mythical creatures like Satyrs or real-life animals like goats or deer.
Basically, faunus are creatures that are closely associated with forests and nature, and are often thought to be playful and mischievous, just like the original Faunus from Roman mythology.