It is a pocket-sized reference book, covering some of the basics like what to look for in the history for someone with a ROM ("Sudden gush of fluid from vagina" or "water running down the legs"), all the way to specific dosing for infections & chemo. It is divided into 10 main parts (each part with multiple chapters), I will list them here if you are interested:
1. Obstetric Triage
2. Labor and Delivery
3. Postpartum Care
4. Prenatal Care
5. Obstetric Complications
6. Complicated Pregnancy
7. General Gynecology
8. Endocrinology and Infertility
9. Pelvic Floor Disorders
10. Gynecologic Oncology
There are some other useful references afterwards, including a section with sample operative dictations, L&D notes & orders, etc.
I would recommend reviewing this before your clerkship or intern year. Of course, much of the information is cursory and you will need separate study (for example, if you want to know about reproductive embryology), but it is a good launching point with practically useful bits of knowledge. Use anki as you go through it for greater retention.