Terry is too simple

I feel as though I am not fully understanding the depth of Terry's character. From what we've talked about in class and what I have read I understand that she is clearly important but its not really jumping up and me and making me feel it as much as I think I should. I do think however, that Terry is foreshadowing to what Sal's future has in store for him. (she is mexican and he will eventually go to Mexico) Maybe that isn't what is meant of that but thats what I got.