"If your so-called friends urge you to do anything you know to be wrong, you be the one to make a stand for right, even if you stand alone. Have the courage to be a light for others to follow." by Thomas S. Monson

This quote means that  when your "friends" offer you things or tell you to do say bad things, you should follow your instinct and choose what is the right answer for you. In other words it is saying not to get pushed around by others just because you want to be "cool" or fit in. When you finally speak up to say that you don't want to do that certain thing, you shouldn't mind if your alone on it. Even if all your "friends" are calling you names or making fun of you, who cares. Then that means they were not true friends at all because they do not respect your decision. The quote also means that you don't really need people to stand with you in a situation like this because they weren't going to be there your whole life anyway. In other words you should not mind when people are forcing you to do things that are bad. You should speak your own mind no matter what. Also if everyone is the same, you should be different aand stand out, because we all have to stand for something. As you can see on the picture, he is different from everyone else and he is alone at it.