It simply means that the object's velocity is decreasing, and it's important to note that:

* Deceleration is not necessarily a decrease in speed. It can be a decrease in speed or a change in direction. For example, a car slowing down from 60 mph to 30 mph is decelerating. A car turning a corner at a constant speed is also decelerating because its direction is changing.

Let me know if you'd like to explore any of these concepts in more detail!