The answer to your question is the title of the poem.
Answer:
mode is a scale which looks much like a major scale but begins on a different scale degree
Explanation:
modes are alternative tonalities
This portrayal is depicted in the image of the child who, although dead, lifts his fists, as a sign of resistance. Thanks to the oppression, the child is dead in his mother's arms, "with a bullet through his brain". But thanks to the people's undying urge for freedom, he isn't dead after all. He lives in their memories. He lives as a symbol of their desire to break free and their resistance to brutality and tyranny.