len() function, numbers doesn't work with Geany Editor

[buran]

Please read, https://python-forum.io/Thread-How-to-Ex...ython-code
In short, you can execute python code in python shell (i.e. python interactive mode, that is when you have >>>) or save the code in .py file (you can use any IDE or text editor) and execute that file from command line. This is how would you normally write and execute code. python shell normally is used only for some ad-hoc experiment or demo.

When you run in python shell, each line is evaluated and result is displayed immediately. That is why you "see" result.
When you write code in .py file, you need to print in order to get visual output
e.g.

names = ["Karen","John",May","Philips")
print(len(names))
names_length = len(names)
print(names_length)
print(15/3)