I don't know there is a definitive editor for Python but one of the most popular ones would be Spyder which is somewhat similar in it's functions to R Studio.
https://pythonhosted.org/spyder/
For something slightly up from a terminal instance there is also iPython, which has extensive help tools you can access. More complex editors like Spyder can be slower for certain things.
http://ipython.org/
And my personal favourite solution, you can always boot a Python instance inside of an emacs shell.
If you don't mind paying a little bit of money (though not that much), my company recently switched from Spyder to Jetbrain's PyCharm IDE. The increase in productivity and capabilities is worth far more than the pricetag and I strongly endorse it.
There is a plenty of Python editors. For myself, I prefer using Spyder which is a built-in editor inside Anaconda. It is an easy way to Python for beginners.
For building GUI in Python, there is no built-in mechanism but many are working on building libraries for developing GUI.
I use Kivy which is a cross-platform framework. It is an easy-to-use framework with the ability to create applications working in all platforms.
I prepared a book titled "Building Android Apps in Python Using Kivy with Android Studio" available here https://www.apress.com/gp/book/9781484250303 . It is a beginners guide to build Android apps in Kivy and distribute the APKs to Google Play as regular Android apps.