Prerequisites for installing Python3 on Mac
Xcode is Apple's Integrated Development Environment (IDE). You might already have Xcode on your Mac. If not, you can get Xcode from Apple appstore.
Homebrew installs the stuff you need. Homebrew is a package manager for Mac OS
Step 1. Launch Terminal.
Go to Launchpad – Other – Terminal
Step 2. Install HomeBrew
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
Install Python3 with Brew
Enter brew command into terminal
brew install python3
Optional, PATH environment
Set up PATH environment variable, if you used HomeBrew to install Python3, then HomeBrew already added PATH.
Do not change PATH environment if you can launch python3 from terminal.
Add the following line to your ~/.profile file
Usually your Python installation directory looks like this, add it to your PATH