When we think of imagery, we are talking about visual images that are created by appealing to the five senses. An image helps us to imagine what is being described in our own minds. Note how Mora does this in her excellent poem. We can picture the son by such details as his "jog" in the "cold dark" and as he strains "lifing" weights and seeks to "expand" his muscles. There is a strong visual element in this excellent poem that also partly appeals to our sense of touch as we can feel the "cold" weather that he nevertheless jogs through and exercises in. The imagery allows us to picture her son engaging in these activities, and likewise "frowning" into the mirror, thus reinforcing the impact of her poem as we lament a society that creates youths who are unhappy with themselves.