A lot of the other answers made this unnecessarily complex and talked about things irrelevant to the OP, so let me try to be clearer:
Many people think that a higher megapixel camera produces sharper photos. However, for a given sensor size, there's a limit on how many megapixels of actual information can be captured. Exceeding that limit doesn't help. If anything, it hurts, because you have bigger file sizes for no discernible benefit. Companies do this because they can advertise a higher megapixel number to fool people who don't know any better.
Snapsort tries to capture this number as "true resolution". In your case, you have a camera advertised as 16 megapixels, but its true resolution is only 9.7 megapixels. This means that your camera can't capture any more detail than it could if it were equipped with a 9.7 megapixel sensor.
If you bought this 16 megapixel camera over an otherwise identical 12 megapixel camera, say, thinking you're going to get more detailed photos, you were fooled :) Both the 16 megapixel and the 12 cameras are in effect 9.7 megapixel cameras.
Note that this is all theoretical -- Snapsort doesn't actually go and measure the performance of the camera by taking photos using it. Instead, it does some mathematical calculations based on the sensor size to determine its "true resolution".
The "true resolution" is also an upper limit. You may not actually get 9.7 megapixels worth of detail from this camera, but you're certainly not going to get more.
So far, we've talked only about the sensor, but the camera's lens can and does reduce the quality of photos. Going back to our previous example, your camera with a "true resolution" of 9.7 megapixels might be equipped with a lens that lets the sensor capture only 5 megapixels worth of information. This is similar to looking through a pair of blurry binoculars -- even if you have excellent eyesight, you're not going to be able to see the detail you could otherwise. By the same analogy, maybe the sensor can capture 9.7 megapixels of information, but not when looking through this blurry lens.
A company named Dxomark tries to capture this in a metric called "perceptual megapixels". As an example, the Sony E-mount 35mm F1.8 lens has a perceptual megapixels count of 11. This means that whether you mount this lens on a camera advertised as 11 megapixels, or 24 megapixels, or 200 megapixels, you're not going to get any clearer photos out of it.
So, if you're comparing cameras or lenses, you have three measurements you could use to tell how sharp they are:
- Advertised megapixels.
- Snapsort's "true resolution"
- Dxomark's "perceptual megapixels".
Of these, perceptual megapixels are the most accurate measurement, since it accounts for both the camera and the lens, and is derived from real-world measurements. The second-best metric is Snapsort's "true resolution". Ignore the megapixels advertised by the manufacturer, because that's just a number on paper, which might never be achieved in practice by your camera.
More important than all is that sharpness / resolution is only one aspect of choosing a camera. Don't blindly go with the sharpest camera. There are many factors, such as low-light performance, autofocus accuracy and speed, battery life, whether the camera supports interchangeable lenses, sensor size, camera type (SLR, mirrorless camera, superzoom, phone, compact), whether it fits in your pocket, and so on. Don't go just by the resolution of the camera when you make a decision.