Basically a 1D sensor that acquires a 2D image because the camera itself is moving.
In this case, I'd imagine that there are 3 such sensors for RGB.
It makes for easier top-of-atmosphere correction, and can be useful for things other than pretty pictures.
Or a static camera and a moving subject. This same style of camera is used for "photo finishes" in races. The camera is literally the finish line, and the the first pixel to "cross the line" is the winner.
Any type of sensor could be CMOS.
Whereas your normal digital camera has a fixed rectangular array of pixels, and the scanning is just reading them progressively (what's called 'rolling shutter') because it's hard to read them all quickly enough at once. Some more expensive sensors do 'global shutter' which usually has better motion characteristics for video.