Answer:
1) Not to discuss his training with anyone else in the community, including his family. This rule exists to maintain the community's limited understanding of the past and to ensure that the knowledge that Jonas is receiving does not create any unrest or upset the order in the community.
2) Not to apply for release (euthanasia). This rule exists because Jonas is privy to certain information that may cause him to question the values and principles of the community. The elders fear that if Jonas were to apply for release, he could reveal this information to the rest of the community and potentially upset the balance and order of this society.
These rules exist to maintain a level of control and regulate information in the community. The government in The Giver is fearful of any changes or disruption, and the rules are designed to enforce the status quo, which has been carefully crafted and maintained over time.