What does it mean that my cats 100% understand what container their treats are kept in? I can not leave the container on the counter or they will knock it onto

What does it mean that my cats 100% understand what container their treats are kept in? I can not leave the container on the counter or they will knock it onto the floor and tear the lid off to get inside. I am conviced they understand something is hidden in a box. Object permanence is something humans and cats both learn and understand.