What does the author mean by “ symbol “.?

Read the excerpt from "lessons of dr. martin luther king, jr." the simple act of refusing to buy table grapes laced with pesticides is a powerful statement that the growers understand. economic pressure is the only language the growers speak, and they are beginning to listen. , boycott table grapes. for your safety, for the workers, and for the children, we must act together. this passage shows that one purpose of chavez’s speech is to persuade people to stop buying grapes treated with pesticides. to tell people about the financial troubles of grape growers. to urge people to learn more about ways to protect children. to show people how growers and consumers can work together.