True north differs from magnetic north, which varies from place to place and over time due to local magnetic anomalies. A magnetic compass almost never shows true north. In fact over millions of years, magnetic north wanders considerable and occasionally reverses so that the magnetic north pole has been near the geographic south pole at some periods in the earth’s history. In the arctic region, a magnetic compass is not very useful.
To find true north from a magnetic compass you have to know the local magnetic variation and how it is varying over time. For ordinary folk this is difficult (although good maps will have magnetic deviation marked on them).
From Websters Online
Finding true north is essential for accurate navigation.
Hence the metaphor. In life’s journey we are often uncertain where we stand, where we are going and what is the right path for us personally. Knowing our true north would enable us to follow the right path.