The "red bow" is a symbol of a sad and difficult time when a girl named Emily was hurt. People in the town are worried about a sickness spreading from animals, so they decide to check and, if needed, put down the sick animals. The red bow reminds them to fight against this problem and protect what they love. It's a way for them to remember and make sure others don't go through the same sadness.
rephrase like a 9th grader in a shorter sentence