The primary job of a DESCRIBER is to modify, or change, your thinking about the nouns in a sentence.
For example, picture this sentence: The dog plays ball in the field.
Now, picture this sentence: The energetic tan dog plays ball in the lush green field.
Did your mental picture of what was happening in the picture change? Of course it did ~ describers are at work!
Describers are marked by putting a rectangle around them. As you can see, there can be multiple describers within a sentence, and they modify more than just the subject!