In general - the road not taken refers to the path that has not been traveled. The famous poet Robert Frost wrote a poem called "The Road less traveled" in which he talks about times in life when one has to make difficult decisions. When confronted with hardships or even in general, its easy to follow the path that everyone walks on ( do what is easy to do). However, sometimes one has to do things that are not exactly the easiest to do. Doing things that are not easy refers to the road less taken.
