What does it mean when my dashboard battery light comes on?

That's what I was afraid of. Thanks, I will get it checked out.

if the alternator is bad,the more things you turn on,the faster the battery will drain.headlights will get real dim,some things wont work,battery will drain,because you will be running straight off the battery,because alternator is not charging.the battery is for starting your car,then the alternator takes over and works everything,including maintaining charge on the battery.