Here's why:

* Acceleration is the rate of change of velocity.

* Velocity includes both speed (how fast an object is moving) and direction.

So, an object can accelerate in a few ways:

* Increasing speed: The object is getting faster.

* Decreasing speed: The object is slowing down (this is also called deceleration).

* Changing direction: Even if the object maintains the same speed, changing direction means its velocity is changing, and therefore it is accelerating.

Let me know if you want to dive deeper into any of these concepts!