i've never tried in excel. seems like the kind of thing word is better suited for because if you want paper flashcard layout is more important than data.Word has a feature where you can take data from excel and format it how you want. Usually done with addresses, but I think it should work here.
in word you create a grid and size it up the way out want (4 cards per page? 6? 8?) and then put the fronts of the card on "page 1" and the backs of the cards on "page 2". Then as long as you keep the layout consistent you can get the flashcards correct by "printing on both sides".
I just need to format the data so it doesn't because ~8000 flashcards.