Here's why:

* Magnitude: This refers to the *amount* of acceleration, often measured in meters per second squared (m/s²). It tells you how quickly the velocity is changing.

* Direction: This tells you *which way* the acceleration is acting. It's crucial for understanding the motion of an object. For example, a car accelerating forward has a different acceleration than a car braking.

Example:

Imagine a car speeding up. The magnitude of its acceleration tells you how quickly its speed is increasing. The direction of acceleration is forward, indicating that the car's velocity is increasing in that direction.

Therefore, acceleration is a vector quantity, meaning it has both magnitude and direction.