Peter is quickly realizing that being friends with Asians because there a no other black kids in his "culturally diverse" utopian community requires him to either fight for his life or tolerate creepy as fuck Stepford children. Neither of which is he accustomed to.
Jinho doesn't understand that the singing and piano skills his parents have been forcing on him won't seem cool to the other kids. He has fun when he plays so far, and he wants to share it with Peter. He doesn't understand why Peter is dismissive, or what Peter is trying to tell him subtly, and he doesn't know why his parents make him practice so hard all the time in front of his grandparents.