Hey Joe! I believe that this question should not quite be in the Homework questions but I may be wrong anyway, although my answer will be just like it would if it was there. You're gonna have to picture a moving body that is decelerating, which means that |a|=/= 0 and so it's speed its decreasing, meaning that the length of the velocity vector is getting smaller and smaller. At some point velocity becomes 0, and that is the point where the acceleration pushes the body to go backwards and stops it momentarily, and after that moment the body is moving backwards with increasing speed. The velocity vector now is counter to what it was before, with increasing length.