Answer:
Okay . . .
So what this is basically saying is that: Dialogue helps understand the character. And what you're supposed to choose a character from "Stargirl" (I don't know what that is) and figure out what you can tell about the character just from the way they speak.
Example: "Well, don't help me or anything," he grumbles.
You can pretty much tell that the character is grumpy or snooty just by the way they speak. :)