What is a mga pixel? is it related tot he lens or the camera?

Similar to an array of buckets collecting rain water, digital camera sensors consist of an array of "pixels" collecting photons, the minute energy packets of which light consists. The number of photons collected in each pixel is converted into an electrical charge by the light sensitive photodiode. This charge is then converted into a voltage, amplified, and converted to a digital value via the analog to digital converter, so that the camera can process the values into the final digital image. pixel have to do nothing with lens.

It is the count of the number of pixels on the sensor in the camera. The pixels are the light sensitive material that captures the image. In most cases the higher the pixel count the more resolution the image has.

The megapixels relate to the camera itself. Most people think that the more megapixels you can get in a camera, the better quality you get. When in reality, if you have a 16MP camera, then you will get a massive poster-sized picture. So, unless you are making poster sized prints a lot, then a 16 megapixel camera will not be practical.