Heather, it gives someone (whoever you decide) the power to take care of your animals. We have an account set up for the dogs and if anything were to happen to us, that money is used for the dogs care. They can either keep the dogs (which Marks nephew and fiance will do) or find suitable homes for them.
That way, you know what will happen to your pets if you die or are not able to care for them anymore. Did I explain that good enough?