Have in mind that c++ is used for all platforms, you have access to memory using pointers. C# is used for making applications for Windows OS, newest .NET versions are really easy to use with or without much experience for creating graphics or animations. Python is a scripting language, as Hiroshe stated it is probably the easiest of those 3 to learn, you can learn the basics using it
can I use python for creating object priented programs such as calculator we use in windows ?
Try to ask questions in the comments. The capabilities of all three languages are compairable (the difference will mostly rely on the community). Yes, you can make GUI's (a term we use in programming for "graphical user interfaces") in python (using TkInter, or WxPython, Kivy, PyQt, etc..). you can also make applications for tablets and websites for that matter.
That goes for all 3 actually, though in C# you'll need to use .Net or some framework for the GUI's (.Net is almost always implied when your programming in C#), and in C++ you'll have a ton of third party options.