This question asks for your personal experience, so it's best you tell your personal story. But i can give you some ideas:
You might have witnessed some minorities being discriminated, for example religious, sexual or ethnic minority.
Maybe you commented then that you know someone of this group and that they're ok - that would be a good example! Then maybe you saw the other person challenge or change their views. If this ever happened to you, you can just describe it in detail!