'(lang)' is not recognized as an internal or external command

every time i run any language, python, lua, etc this happens, error code underneath

[Running] lua "this is a path, ignore/tempCodeRunnerFile.lua"
'lua' is not recognized as an internal or external command,
operable program or batch file.

[Done] exited with code=1 in 0.02 seconds

code:
function cube(num)
return num*num*num
end
print(cube(3))

please help, i really wanna run code :/