Fear of failure is simply what it self-evidently appears to be.
Sometimes, though perhaps less often, people fear failure in the interpersonal realm of relationships, as well. Fear of failure can be rational or irrational, or have mixtures of both as emotions often do. When you experience a fear of failure, it's important to acknowledge it to yourself. Keep in mind that this technique only works as an ongoing monologue within yourself. You obviously can't point out your successes one time and expect the fear of failure to go away.