"Taking a screen shot" simply means capturing a picture of exactly what's showing on your tablet or phone screen. There are times when this feature comes in very handy. Maybe your screen is showing an error that you'd like to preserve so your tech friend can evaluate it. Or you see a killer recipe on the web. Or you'd like to grab an image from a Skype or Facetime session. The uses are endless. Fortunately, it's very easy to do. The exact technique varies by device, but I'll show you the iPad way.
Simply press the Power Button and Home Button at the same time (see photo). If you did it right you should hear the familiar shutter click sound and, when you check your Camera Roll in Photos afterward, there it is!