I am install npm to start a new front-end dev project, and I would like to know what that command is. Thank you!
gcc is GNU Compiler Collection. GCC is a must-to-have in order to compile most of the applications unless target OS is Windows.
which is a UNIX command. It shows the path to the command you specify as an argument. That is, if gcc is installed in /usr/bin then which gcc will give you:
/usr/bin/gcc
Otherwise (if there is no gcc installed), you will get no output.
P.S. Use search engine of your choice, that is easily available information.