Taking a screenshot in NOX is fairly easy, all you have to do is click the scissor icon which can be found on the sidebar, or press CTRL + 1. Users of Android emulators such as NOX do this so that they can play games that are usually only available on mobile devices on their desktop PC. An Android emulator is a piece of software that allows you to emulate - in other words, simulate - an Android device.
NOX App Player, often referred to as NOX, is an Android emulator for both Windows and Mac.