I cannot brainstorm anything
Of course you can. Start by defining what it means to take pride in one's heritage, and what it means to have prejudice against others. Then, list all the examples of each that you can think of. Then, think about the items on the list. Do any of them overlap? If so, why did you put them in both categories. Also, ask yourself questions that might provoke promising lines of inquiry. For instance, is it really true that all cultures are equally good, as the prompt implies? We don't usually say this of individual values. A person who beats his wife is not viewed as holding to an equally good morally code as a person who treats his wife (and women in general) with respect. Should a culture that fosters the former behavior be treated equally to one that fosters the latter? And so on. As you think about how you would answer these questions, you will begin to get a sense of what you want to say about the topic.