Python 3 introduced the idea of "type annotations," and as of Python 3.6, you can annotate variables, not just function parameters and return values. The idea is that you can put a colon (:) and then ...

Enhancements to Python types Python’s type hinting system has expanded in functionality and utility with each new version. Version 3.13 adds three big new changes.

All you need to do is open the Terminal application and type python to get started (type ctrl+d to exit Python). Learn Python the Hard Way has everything you need to start programming in Python.