If Willa and I hear from our parents then we will let you know.
Adjectives are descriptive words that describe other words and answer a question.
Thus, in your sentence, the adjective is the word red, as is tells the reader what color the shirt is.
This lines could be seen as examples of sensory imaginary. More precisely it is connected to smell because of the potato and sight because of how this person is found "sitting, surrounded.." it might be said that the combination of these two images could give the reader a vision of what the writer is trying to convey.
