What does Nina represent?

Nina is a symbol of the frustrations that Deaf people endure in spaces where they are the only Deaf person, despite the good intentions of some of the people around them. Nina is one of Iris's classmates and the one who has most taken initiative in trying to learn how to sign. However, Iris is very frustrated by her insistence in doing so (often poorly), and is suspended for pushing her when she gets frustrated with her insistence early on. Bennie eventually softens Iris a bit on the notion that she is trying her best to communicate with Iris, but her frustration remains and, indeed, it must be frustrating for Iris to try to interact with people like this.