Once you enter the Archive, you will see all cards that have been archived in this Board. You can look for a special card using the Find field. You can scroll down to the bottom and the search field will be always on top. Archived cards now also display a status on it's front.
From this place, you have the possibility to send archived cards back to the Board. Click on Send to board button to achieve that.
You can clearly recognize cards in MyBoard or Search (in the image below) section that has been archived in the original Boards.