An unrealized gain or loss is a potential gain or loss at any point in time between the recorded sale or purchase and the receipt or issue of payment. No automatic postings are made to track unrealized gains or losses on foreign-currency transactions.
Not all businesses need to track unrealized currency gains or losses. You should check with your accountant to determine whether your business needs to track them.
The Currency Unrealized Gain/Loss report lists the gain or loss made on each foreign currency. You can then use this information to make adjustment postings to each of your foreign-currency accounts for your balance sheet and also to a profit & loss account.