In the opening chapter it is revealed to the reader that Jonas is feeling apprehensive about something that will be happening to all of the Elevens in this dystopian community. It is clear however, that he has a real mix of feelings about this forthcoming event, because alongside his apprehension he also feels more positively about it as well:

Now that it was almost upon him, he wasn't frightened, but he was... eager, he decided. He was eager for it to come. And he was excited, certainly.

The apprehension that he feels serves to increase the suspense and tension that the novel creates as the reader waits to find out what this event is. It is only later on in the text that we find out it is the Ceremony of the Twelve, when all of those who reach the age of twelve are given a specific job or role within their community that will be theres for the rest of their life. Jonas is of course concerned and deeply curious about what role will be given to him and whether it will be something he will enjoy or not.