A dream that you fail at something usually has to do with a fear of failure in real life.
For example, dreaming that you fail a test can reflect concerns about how you will perform at a new job or about how you are managing a current relationship.
A dream about failing can also be a message that if you continue to behave in a certain way, your actions will lead to failure. Your dreaming mind is telling you to pay attention to your actions and to the consequences that they may bring. For example, you may be speaking to a family member in a way that will encourage them to reject you.
Dreams about failure can mean that you are placing too much pressure on yourself. If you find yourself having recurring dreams about failing at something, you could be imposing unreasonable expectations on yourself. You might also be worried about how well you can compete with someone at a particular task. Your dream is telling you that you should learn to accept yourself as you are.