The spell allows a witch to send their mind into an animal with which she have created a bond. The witch will see, hear, sense and smell everything the companion perceives for as long as she manages to hold her concentration. The demand on the witch is so complete that they can do nothing but sit still and concentrate and she is also not aware of what is happening with her until they release the spell as she has completely been enveloped by the companion's senses.
The witch can, to a limited degree, guide the animal companion. She can make the animal look in a certain direction or even move to where she wants. It is no form of control but a gentle compulsion. The animal companion is still quite sovereign in its decisions and may refuse.