The Parts in the Sum of the Whole - S5-E16
Continuity mistake: In this episode, Booth and Bones are telling Sweets about their "real first case" together - the case where they actually met for the first time. During this episode, Booth, Bones, and Angela take some evidence to Caroline, and Booth introduces them both (most importantly Brennan) to Caroline. However, in season 1, episode 19, "The Man in the Morgue", (which would have taken place after this initial first meeting) when Brennan is accused of murder in New Orleans, Booth has Caroline fly to NOLA to be Brennan's lawyer, and he introduces the two of them. If they had already been introduced during the first case Booth and Brennan worked on together, they would not have needed to be introduced here; they would have already known one another.
Answer: Since the palatine bone is a bone that helps form the mouth it has a lot to do with speaking. The shape of it differs a lot depending on your ethnic background. I would guess that they, in the show, meant that the person's bone tells that they were Japanese and that it was "made for the purpose of speaking Japanese." That's what I'd assume anyway. I've studied molecular biology though, so I'm not an expert on bones.