Summary: The RBT Ethics Code is the set of rules that govern how you behave as a technician. Most of it comes down to a few habits: protect the client, stay in your lane, guard confidential information, and bring problems to your supervisor instead of solving them yourself. The exam tests this constantly, and almost every "what should the RBT do" question has the same answer hiding in it.
Let me be blunt about why this section matters. Ethics questions are where a lot of otherwise-prepared people lose points on the RBT exam, and where new techs get themselves in trouble on the job. The technical content rewards you for knowing procedures. Ethics rewards you for knowing your limits. Those are different skills.
You signed an agreement to follow the BACB's ethics requirements when you got certified. That agreement isn't a formality. It's the thing standing between a vulnerable client and someone who decides to freelance.
What the code is and where it comes from
The Behavior Analyst Certification Board (BACB) writes and maintains the ethics requirements for RBTs. The code covers your conduct on the job, your obligations to clients, the limits of what you're trained to do, and what you owe the people who supervise you.
Don't memorize section numbers. The BACB updates the code periodically, and the exam isn't going to ask you to recite "Code 2.05." It's going to put you in a situation and ask what you do. So learn the behavior, not the citation.
That's the free preview of Ethics and RBT Code. The complete guide, plus all 851 practice questions and 3 full exams, is in the study pack and the book.