The information given in class for yoga postures is endless. I used to think the only reason my teacher gave me this information was so that I could stay safe, move further in the pose and get strong. While this is true, the other reason for the instruction is so that, as we do the pose, we can move from the physica body to the more subtle body (the mind, intelligence and the consciousness).
The sanskrit word Suksma refers to the subtle body. The subtle body is much harder to identify with than the physical body.
We can touch and feel our physical body. When I tell you to move your foot, you move your foot. But when I tell you to extend the skin of the sole of the foot forward as the heel extends back, you make a face. Effort to think about something you have NEVER been asked to identify presents one with deep concentration. Then one day, you feel the skin move. You no longer make a face. Moving to the inner place where you are able to find subtleties you become serene instead of troubled. The more subtle the movement, the more we move inward. Involution brings introspection. Involution then leads to evolution. Introspection is the purpose of the yoga practice and when we take it from a physical gymnastics to a method to move inward, the ability to find our subtle body and a more satvic state is achieved.
Instructions make more sense to us and become more meaningful as our understanding deepens. A teacher is constantly layering information so that you can go deeper into a given pose. Build your experience with a regular practice. Listen and be attentive.