This refers to trading in forex, i.e. buying/selling USD, GBP, etc., and not buying or selling products or services priced in USD, GBP etc.
See: https://www.livemint.com/Politics/T...of-forex-trading-through-foreign-portals.html
From the article:
There are websites that accept payments through credit cards and allow an individual to bet on currencies. Any profit or loss is settled through the person’s bank account in India.