Go to the Python download page. Click the latest Python 3 version.
When the file has downloaded, double-click the Finder icon in the bottom-left corner of your screen
Double-click the Python 3 install file that you just downloaded.
Keep clicking Continue through a series of information and legal screens.
Click Agree to the licensing terms.
Enter your name and password for your Mac, then click Install Software.
When the installation is complete, click Close.
To be sure Python is installed correctly, begin by double-clicking the Finder icon in the bottom-left corner of your screen.
The right-hand panel shows all the applications. Scroll down to the bottom and click Utilities.
When a third panel opens, find Terminal near the bottom. Click it
When the Terminal window opens, enter python3.
If information displays for the Python version that you downloaded, the installation is correct.
Congratulations! Python is now on your computer. It's ready to run the Python programs that you write.