The Aura is the human energy field. However, all living beings have auras but we usually refer to human aura when we talk about it.
You can see the aura or energy field of any living plant or animal. As you practice seeing the energy field, it will get easier and easier for your eyes to see it.
As you keep practicing this, you will begin to see this most dense part of the aura – it’s the first layer and many refer to it as the etheric body or etheric double because it is the energy body that matches your physical form.