You can get started with as little as the camera on your phone, but each class will include specific requirements in the description. Generally, it’s helpful to have a good digital camera with manual mode, a changeable lens and a zoom lens kit, a flash with manual mode, and a through the lens (TTL) kit.
If you’re already a photographer, you’ll probably have all this equipment and might need to get a specific lens or external flash, tripods, lighting equipment, or other gear depending on the course you’re taking. Camera and other photography gear can get really expensive, so think about borrowing, buying second hand, or just getting the minimum required before you’re sure that you’ll continue with this specific field of photography in the future.