This refers to bills payable by entity concerned in foreign currency. This may generally arise due to imports of services or goods by the entity whose settlements are to be made in foreign currencies.
For example, XYZ Pvt. Ltd. purchased machinery products from foreign vendor ABC Ltd. of USA, whose settlement are to be done in USD after 3 months and the bill amounts to USD 5,00,000. This $ 5,00,000 is foreign exchange payable for XYZ Pvt. Ltd. as it will require it to pay USD 5,00,000 in upcoming three months.