Bikkurim, Chapter Two, Mishnah Eight
The laws regarding a domesticated beast (a behemah, such as a cow) and those governing a wild animal (a hayah, such as a deer) are different. The rest of the chapter discusses a koy an animal that is in some ways treated as if it was a domesticated beast and in some ways treated as if it was a wild animal. Because this animal doesnt fit neatly into one category, how it works must be discussed. Besides, the rabbis just love to categorize and they especially love to talk about things that fall in-between two categories.
Some scholars say that a koy was a type of ram while others say it is the cross-breed between a male goat and a female deer. In any case, its precise identification is not crucial for understanding the Mishnah.
This mishnah is just an introduction, one which doesnt really provide any information. There is no commentary below.
A koy is in some ways like a wild animal (hayyah); in some ways it is like a domesticated animal (behemah); in some ways it is like both a behemah and a hayyah, and in some ways it is like neither a behemah nor a hayyah.