Baba's description of Amir is fairly direct. Baba notes that Amir does not stand up for himself. He lets Hassan do the dirty and challenging work of fighting off the thugs and bullies that intimidate him. In observing this tendency, Baba notes that Amir does not embody any values that Baba finds desirable, such as being good at sports and demonstrating physical strength. Amir is a thinker, a poet, a words- person. These are qualities that Baba does not respect and does not "get." It is in this light where he observes that a child who does not fight back or show defiance when in trouble becomes someone who lacks values as an adult. In a reminder of story's opening of "to be good again," the father's description of his son is a reminder of the redemption idea that runs through the story.
The quote is a reflection of how Amir was as a child, something that is later confirmed with how Amir does not stand up for Hassan when he is being raped and violated. For his part, Amir overhears the quote and is deeply hurt. Perhaps, this is a reflection of how accurate the quote might be in describing Amir, and becomes the subconscious driving force for him to "become good again.