The acceleration of a free-falling body with no air resistance is 9.8 m/s² (meters per second squared). This is also known as the acceleration due to gravity, often represented by the letter g.

Here's what it means:

* Acceleration: A change in velocity over time. A free-falling object is constantly speeding up as it falls.

* 9.8 m/s²: Every second, the object's downward velocity increases by 9.8 meters per second.

Important Note: This value is an approximation and varies slightly depending on factors like altitude and latitude.