Its the class that django uses to auto reload the development server whenever you make code changes .
Specifically, determined within the get_reloader method where watchman is an alternative for linux / macOS
If you’re using Linux or MacOS and install both pywatchman and the Watchman service, kernel signals will be used to autoreload the server (rather than polling file modification timestamps each second). This offers better performance on large projects, reduced response time after code changes, more robust change detection, and a reduction in power usage.
(Runserver docs)
No idea why its in red in pycharm but if you really wanted to you can disable it with the --noreload flag