It's primarily an API on which developers can build plugins in Python (though doing a lot of useful stuff actually requires calling out to Applescript, of all things). There's no visual workflow-builder like in Alfred, although you _can_ set up triggers for Automator workflows.
Why are Flashlight plugins written in Python? (I'm asking out of curiosity; I like it.)
JS and Ruby are bundled with OS X as well and Apple started offering some JavaScript APIs in 10.10 for stuff that could previously only be done with AppleScript.
No particular reason. The API currently involves importing `plugin.py` files and calling functions in them, which makes it a bit simpler, but it should be possible to bridge with other languages.
I've considered using Javascript for Automation, but there isn't a huge amount of documentation around it, so it hasn't been that valuable.
