What do the three balls outside a pawn shop mean?

The Medici family in Italy were moneylenders during the Middle Ages and operated pawnshops throughout Europe. Legend has it that they also slew a giant for King Charlemagne using three bags of rocks. These three bags became stylized into three golden balls, which became a part of their family crest and the source of the symbol we see today.

Back in Europe it was well known most people did not know how to read and write. So when people saw this symbol hanging in front of a shop, they knew it was a safe place to go to trade.