Unlike Windows, Linux does not have files that are executable, all files can have this attribute. So for example, I have a python file that is just a text file, and I will to be able to run this from the command line, If I look at the file using ls -al:

  ls -al

I will see something like this:

  "-rw-r--r-- 1 pi pi 4452 Jul 25 17:46 40x2_LCD.py"

The permissions for this file are:

  "-rw-r--r--"

This file has three sets of permissions:

  User -rw  |  Group -r-  |  Others r--