You already know 人, a single person standing in profile. 北 simply doubles it, back to back instead of following in line like 从: two people who have turned away from each other. "The back" was the very first meaning of this shape — scribes only later borrowed it, purely for its sound, to write the compass direction north.
A piece of culture
Turning your back to run 北's oldest meaning, "back", never fully disappeared. 败北 (bàiběi), literally "defeat + back", is still the everyday word for "to lose a battle" — because a beaten army shows its back as it flees. Sun Tzu's Art of War warns generals, two and a half thousand years ago: 佯北勿从, "do not chase an enemy who feigns retreat" — using both 北 and 从, a character you already know from this very chapter, exactly as the oracle-bone scribes first drew them.
Use it in a real word
北京
Běijīng · bak1 ging1
Beijing — literally "northern capital"; you already know 北