From vague memories - been quite a while since I built anything using make, but IIRC that'd mean that there's no section in the makefile that describes what is supposed to be done in the case make is called with the argument 'menuconfig'. Might be that your makefile's been mangled...

As to those impressive command lines - you know and remember what you use...
Over time you find and learn what various tools there are and what they in general do, switch details and detailed behaviour is found in the man-pages.
Often, at least for me, the long command lines are grown in stages, ie run first part and see what you get out, figure out what is needed to process that output further into the next stage, tack on that command, rinse and repeat until you have the wanted final output. It's programming, only that the stages are stacked horizontally and separated by pipes (|)rather than vertically and by newlines.
the various command line programs are essentially the same as functions in a programming language.
The shell, just like plain C, offers some basic functionality for loops, comditionals etc, but the power to do much, without a lot of effort/coding, lies in the function libraries / command line programs.