To aim at something in a dream can symbolize working toward a goal in waking life.
If in your dream your aim is good and you are able to hit your target, it can be a sign that you are confident that you have the ability and the resources to achieve what you desire.
A dream that your aim is faulty or that you miss your target can be a message from your unconscious that you are approaching a problem the wrong way.
Try to think of alternative solutions. Dreaming that you aim an arrow or a gun at someone, but that you do not shoot it, can mean that you are upset by the actions of another person, but that you do not know how to go about confronting them.
If someone aims a weapon at you in a dream, it can mean that you feel that you are being victimized in waking life.