The 7M3K (official model: ILCE-7M3K) is the Sony Alpha 7 III kit version.
It is a full-frame mirrorless camera that comes bundled with a kit lens (usually the 28–70mm zoom lens). The camera itself has a 24.2MP full-frame sensor, strong autofocus with Eye AF, 10 fps continuous shooting, and 4K video recording, making it a popular all-rounder for photography and videography. The “K” simply means it is a kit package (camera + lens), while ILCE-7M3 refers to the body-only version.