What does it mean when battery light sporadically comes on in a 2009 jeep wrangler?

Usually that means either, The battery has a dead cell and needs changing, The battery is being over taxed and is experiencing large voltage drops, or the alternator is malfunctioning. The alternator could be charging the battery and then not charging for a long period of time. This will cause the battery to get low pinging the warning light then later shutting off when the alternator starts charging again.

There are many auto part stores you can take it to, for a free test of the battery and alternator.