You would enter the information on Schedule 1 (Form 1040) Additional Income and Adjustments to Income, Line 8 as an ordinary gain or (loss).
The journal entry to record a foreign exchange transaction gain varies based on whether the gain is realized or unrealized: Realized Gain: A realized foreign exchange gain occurs when an actual transaction is settled at a more favorable exchange rate than initially recorded.
FX gains and losses are reported on the income statement. as a separate line item or they may appear under the “Other Comprehensive Income (OCI)” category.