By default, the backside of the card has the first "sense" from JMDict on it. This sense is supposed to represent the primary meaning of the word. You can also add/replace that with the other senses by editing the flashcard, or you can add your own notes to the back.
I've found using the first sense works pretty well. Having the whole definition on the back is way too much for your brain to process, but the first sense is usually only a few words that encapsulate the meaning of the word pretty well.
I've found using the first sense works pretty well. Having the whole definition on the back is way too much for your brain to process, but the first sense is usually only a few words that encapsulate the meaning of the word pretty well.