His use of the concept Symbol here is very different from the use in terms like "symbolic reasoning." A symbol for Vervaeke is not just any linguistic signifier or an algebraic variable. It's more like the kind of use in "the lion is a symbol of strength" or the Christian cross.
Vervaeke's first example of a Symbol in this sense is the scales of justice. He looks at that Symbol from an embodied cognitive science perspective, claiming that it's not just a nice metaphor. The Symbol identifies justice as involving balance, and we can use the link to the vivid embodied image of the scales to activate our actual capacity for balance. Physical balancing is associated with the brain's cerebellum, and Vervaeke explains that attuning to the Symbol of the scales is a way to light up these neural circuits to bring our learned sense of balancing to bear when making ethical decisions.