A descriptive quote is simply a quote that throughly describes and gives details about a subject or in this case a character.
Without more information on your assignment, my best understanding is that your teacher is looking for a quote from whatever literary piece you are reading that best describes each of the characters.
The author states that both Granuaile and the queen were not young but proud and remarkable.
I'm not sure if that's enough but I found it on paragraph 9
