In the background
zshTerminal shell
◐ Close the app instead
A command line, usually in Terminal or a developer tool.
What it is
Each Terminal window, and many developer tools, run a shell like this one to run commands.
If you close it
That Terminal window or tool loses its command line, and anything running in it stops.
The verdict
◐ Close the app instead. A part of an app. Closing it alone breaks something, so close its app.
In Activity Monitor
zshbashfishsh-zsh-bash
From Procession’s guide, in the words the app shows.