What is a python binary

Hello,

I am exploring how to create virtual environments in Sublime Text3 and found a package called Virtualenv. I have a question about creating a new virtual environment. Here is the documentation.

Creating a virtualenv

Choose Virtualenv: New (or Virtualenv: New (venv) for built-in virtualenv), type a destination path and select a python binary. The new virtualenv will be activated automatically.

My question is, what is a python binary and what is its importance (I cant seem to find the term anywhere online). Here is what pops out after I specify the folder name and thus the destination path.

Thank you so much.