The most important part of Jupyter for our purposes is the Notebook, a tool for developing and documenting code across a variety of languages. Take a moment and check out a gallery of fantastic notebooks to get an idea of what it is used for.
All users can install Jupyter according to the installation instructions in the Jupyter documentation. I will refer to this as the "Anaconda method" because that is the package manager recommended in the official documentation. This should work smoothly, especially if you primarily intend to use Python in Jupyter.
However, for Mac users, I would recommend an alternative installation method (the "Homebrew method") that should make it easier to support alternative languages.