You should tell someone when they say something offensive.
Brandon hears his brother say something in front on a classmate of theirs that Brandon knows would offend them.
Brandon wants to talk to his brother.
Brandon takes his brother aside and explains that what he said would cause offense.
Brandon tells his brother that they should leave but doesn't explain to him that he was being offensive.
Brandon's brother understands that he was speaking hurtfully and starts being more careful with his words.
Brandon's brother doesn't understand that he said something wrong and continues making that mistake.