The Free Peoples player can use a Character result on an Action die during the Action Resolution phase (or can play an appropriate Event card), to hide a Revealed Fellowship, turning the Fellowship Progress counter to its Hidden side.
Note that using a Character Action die to hide the Fellowship does not allow it to also move during that action (and the used die is not added to the Hunt Box). The Free Peoples player must later use another Character die to move the Hidden Fellowship once again.
Remember that it is necessary for the Fellowship to be Hidden in order for it to move.