What do Jonas' rules tell him about his assigned job in The Giver?

Jonas’s rules tell him that his job is different from others and will involve secrets.

At the age of twelve, all children in Jonas’s community are given the job they will have for life.  Jonas’s job is an unusual one.  He is chosen to be the community’s Receiver of Memory.  He has no idea what that means. 

While most of his classmates get thick folders or binders of instructions, Jonas gets one sheet of paper.  On the paper are eight rules.  They baffle Jonas.  He knows that every Twelve will get instructions telling him or her where to go and when, and his do contain that information.  He is to go immediately to the Receiver’s Annex and come immediately home.  He is also not allowed to tell anyone anything.

Do not discuss your training with any other member of the community, including parents and Elders. (Ch. 9)

This tells Jonas that his job is a secret.  He is not even allowed to tell Elders about his training.  Although Jonas does not give too much thought to this yet, it has mind-blowing implications for later.  He is about to learn things about the community that no one else knows.

Jonas notices that his rules will affect his relationships.  He realizes he is not going to be spending much time with his friends other than at school, and won’t have much recreation time.  More interestingly, Jonas has some strange rules that seem to contradict the community’s rules.  The community has prohibitions against lying and against rudeness, but Jonas has rules that tell him he can lie and he can ask anyone any question and they have to answer.

He had never, within his memory, been tempted to lie. .. No one did. Unless ... Now Jonas had a thought that he had never had before. This new thought was frightening. What if others--adult-- had, upon becoming Twelves, received in their instructions the same terrifying sentence? (Ch. 9)

Jonas realizes that he can ask people if they are lying, but he would never know if they were telling the truth.  He is disturbed by this rule in his instructions because it seems to turn everything he knows about his community on its head.  He hasn’t even begun training yet, and he is already questioning things.  The main thing Jonas's rules tell him is that things are not what they seem.