As others have mentioned, a lot of it will depend on your institution.
The core clerkships that you are required to complete are the same everywhere. These include internal medicine, family medicine, surgery, OB/GYN, family medicine, neurology, pediatrics, and psychiatry. You will do these clerkships no matter where you go. Some institutions also have other requirements that they may add to that; for example, a rotation in emergency medicine is not uncommon.
Where you rotate and what kind of service you're on will be very institution-dependent. Whether or not you have a choice in that will also be institution-dependent (at my school, we didn't have any choice in that). If you're at a fairly large academic system, you may rotate with one or two other medical students, if that. For smaller systems, there may be several medical students on your team. An attending may be responsible for supervising a couple of medical students or only one. At the institution I'm currently at, for example, we typically have 3-4 medical students rotating on our inpatient psychiatric unit, but we have 3 different teaching teams, so an attending may supervise 2 students at most.
The length of the clerkship will also vary from institution to institution. Generally, you will likely spend time on a couple of different services during your clerkship. At my school, for example, our internal medicine clerkship was 3 months, but that time was split among several different services: 1 month was general internal medicine and the remaining 2 months were split into 2-week blocks on various services (e.g., general outpatient internal medicine, inpatient specialty services, etc.). The goal is to get you a broad exposure to several areas of medicine during your clerkship. Again, how this specifically works out will depend heavily on your institution and the individual department.
tl;dr: There's a lot of variety here, and it's difficult to say what, specifically, you will experience. The broad strokes of what is expected during clerkship experiences is spelled out, but medical schools have wide latitude with respect to how they're going to implement those guidelines.