Do you know who Bruce Lee is? He was a major actor in the 1970s, starring in movies thanks to his incredible martial arts moves and killer good looks. He wasn't just another superstar, though—he was America's first real Chinese icon and hero. In other words, dude was a big deal, and while he remains widely known for his masterful martial arts skills, an important part of his legacy is his ability to break into American cinema as an Asian man.
Bruce Lee comes up time and again in this story, thanks to Hà's brother Vu who is so obsessed with Bruce Lee that he calls himself Vu lee. Hà finds this funny and strange, and she doesn't understand why Vu wants to look like Bruce Lee, or why other people respond to Lee in such a positive way. Vu, of course, gets it: Bruce Lee is a model for how to be accepted as an Asian man in the United States, a model that Vu would very much like to emulate, thankyouverymuch.
So on the one hand Bruce Lee is a symbol of acceptance, of the potential for successful integration into the dominant American culture. But on the other hand, he represents just how hard it is to be accepted in the United States, how few options there are for Asian people to gain acceptance, and as such, how prevalent racism against Asian people is in the United States at the time the book is set. That Vu identifies only one way to earn respect from his peers, and that this is by mimicking a movie star to the best of his ability, symbolizes just how hard it is for Hà and her family to fit in once they arrive in the States.