In Aristotle’s De Anima, he makes it very clear that the soul is not a physical being or something that can be touched but rather it is the form for all living things. That the soul is what makes things alive things like plants, animals, and to a broader extension the ancient greeks believed anything with movement such as fire and magnets for example since it was in motion had a soul. That the soul was responsible for the thing we do but it was a quality of ones body(for clarification this simply means that the soul can be thought of as the “form” for living things). And Aristotle makes it clear that he does not believe a soul can change from person to person after death(human soul to bug soul for instance).
He talks about potential and actualization of the soul. A oven at rest doing nothing has potential and only when it is doing the thing it is mean to do does it then fulfill its potential. Or for example you have a man named Eric who wants to learn Russian. Eric does not know Russian but he can learn it and has the potential to do so and once he does so he will have actualized his potential to know Russian.
Aristotle also makes the distinction between first and second actuality, so once actualization is achieved there is two different states Aristotle would say. The first when one knows something but isn't using it like “I know calculus but I'm asleep”. The second he would say is that which you know/have and are using “I am actively doing calculus”.
Aristotle would classify the soul as being a first actualization/actualized because it is possession of someone but it is not being used but has the potential to be used. That the soul is a part of the body, in the same way that our liver or kidney is apart of our body. The very being a human requires a soul, in the same way that an eye requires sight(its actualization). An eye is used to see, but when we are asleep it is not being used for that purpose in the same way the soul is not used for something, but once we awaken from sleep the eye has the potential to see. However if we were to remove sight from a eye “it is not longer an eye” Aristotle writes. Because it loses its essential being, and yes the eye is still an eye but what good is it? Its only an eye in name but not in function, Aristotle would say. He would say that the soul is not a substance like wood or rock or blood, but rather it is the actualization of the body. Without it it the body only exists in name, and with it we have the potential to do with our lives how we wish is what Aristotle would say.