web development – Run Python Script on Uploaded File

I would like to have a website whose entire page consists of:

  1. accepting a file as drop & drop upload;
  2. run my Python script on that file in the background;
  3. make the output file of the script available for download.

(Check the mockup below)

As a hardware developer I have no idea whatsoever what keywords to use to ask a Fiverr Developer for advice. Since anything “web” is complete black magic.

Can someone point me in the right direction?