How do big websites use Python?

I'm planning a website that uses predictive technologies and machine learning to calculate probabilities. I created a code in python using some libraries where it predicted the name of a client based on the characteristics (age, sex, etc), I would implement this code in a web application where the official language of the site is not python (is not defined yet).

What I would like to know is: how can YouTube, Google, Instagram and Netflix be able to use python technology in websites or apps? With django? Or do they use something to externally implement the functions in python? If so, what is this technology called?

If possible, I would like to know the same about ruby on rails.