The fee transaction is a cost that is offset for tax purposes. It is normally a fee imposed by an exchange. The fee is an indicative (estimated) market value when the coin(s) fee was charged.
On this screen it is possible to unclassify existing transactions; this will preserve the main information of the transaction and will allow you to reclassify it as a different type of transaction without needing to re-enter it. i.e. Fees -> Unclassified -> Trade.
You can auto use the auto-value feature for looking up historic prices.
For more information on auto-value click here.