What does she mean by "use your words"?

Native speaker’s answer
Rebecca
This is an expression often used with children, to remind them to not get emotional/frustrated and to express themselves clearly by talking it out. This is because children often do not use logic when they are emotional, so adults will remind them to communicate using words. It's considered insulting to say this to adults, but in this case it's okay for the little girl to use this expression with her grandfather because she's a child and is saying it in a gentle way. Ex: Honey, don't get frustrated. Use your words. Ex: Remember to use your words.