What is the .sh File Extension?
.sh is a file extension for shell scripts for Linux and other UNIX-based operating systems (BSD, macOS).
How do I open an .sh file?
You can edit a .sh file with any source code editor.
To run an .sh file you need a Unix shell. Generally you don't run a .sh file on Windows; cross-platform software that distributes a .sh file will also distribute an equivalent .bat file for Windows, e.g. Automatic1111's Web UI for Stable Diffusion is distributed with both a a webui.sh for Linux and a webui.bat for Windows.