Exchange Rate Discount (Seoul)

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Does anyone know what "exchange rate discounts and coupons" are?

I'm taking the KRail to Busan and the pass has this discount as an additional benefit.
"Exchange Rate discount Service of WOORI BANK : 50% discount(only $,?)"
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Money Exchange (2)
Money
Exchange (2) Shinhan Bank Nationwide Protected content 30~60% Preferational Rate
Hana Bank Nationwide Protected content 50% Preferational Rate

What in the world is a 60% Preferential Rate?
Does that mean I get 60% extra? Seems too good to be true...