This happens if the phone and the battery are not correctly communicating with each other. This could be caused by a bad connection between them, or a problem with the battery (or least likely, a problem with the phone).
First, try this: turn off the phone, take out the battery, wait a minute, then put the battery back in and turn the phone on again.
If the problem still happens after that, bring the phone to a Verizon store and ask them to try a different battery in the phone. If that fixes the problem, you need to buy a new battery (and if it doesn't fix the problem, then there is something wrong with the phone).
First, try this: turn off the phone, take out the battery, wait a minute, then put the battery back in and turn the phone on again.
If the problem still happens after that, bring the phone to a Verizon store and ask them to try a different battery in the phone. If that fixes the problem, you need to buy a new battery (and if it doesn't fix the problem, then there is something wrong with the phone).