Everything’s fairly straightforward. You have 55 multiple choice questions that are stimulus-based. With general knowledge about the trends and important events in US History, you should do just fine. I didn’t study at all for the exam and I was totally fine. That said, that doesn’t mean you shouldn’t study but the exam is going to be easier than the classwork so it’s really not that hard. After the multiple choice, there are four SAQ (short answer questions) where they ask you general questions about time periods. For 2017, one of the SAQs was about the Reconstruction and post-Reconstruction era. If you want an example, APCollege has released the 2017 AP Exam essay questions here. Then, you have a DBQ and an LEQ. Once again, you can see the 2017 essay prompts at the link above. The essays should be the same as the ones you write in class but it’s easier because it’s usually more general and don’t require the amount of specificity that in-class essays usually need.
In conclusion, you’re going to be fine. If you’ve done decently well in class, then you’re definitely going to get at least a 3. If you have trouble, go to your teacher or organise an APUSH AP Exam study group. If anything, you can ask me if you have any questions. Good luck!