When an item is carried at fair value, its recorded amount is updated at each reporting date. The difference between the old and new value is the fair-value adjustment, and it is recognized as a gain or a loss. The adjustment applies to things such as investments, warrants, embedded derivatives and some contingent payments.
It does not mean that cash changed hands. A company can report a large gain or loss from a change in its estimate, without receiving or paying anything. The adjustment can also reverse in a later period if the estimate moves back.
The location in the statements varies. Some adjustments appear in operating results, and others in a separate line for other income or expense, so the headline profit or loss can mix operating performance with changes in estimates.
Look for the line in the income statement and the matching note, work out how much of the result is non-cash, and judge the business on results with these items separated.