Fear is a voice inside of you saying "I think something bad is going to happen"
Fear can be thought of as the root of all other "bad" feelings. When you're not meeting your needs, then you don't feel totally safe and secure and that generates Fear.
Like all primary feelings, Fear is good because it lets you know that you need to take care of yourself and the people in your life. It's like a voice saying "You need to take action!".