What Shell Your Mac is Using?
Every Mac comes with a Unix shell that provides a command line interface. Macs running macOS 10.15 and later use Zsh by default. Before that, Macs used the Bash shell by default. Of course, no matter what version of macOS you’re using, you can change the shell your Mac is using.
What shell is your Mac using? Open the Terminal application on your Mac.
At the prompt, type
echo $0