Here's a breakdown:

* Acceleration is the rate of change of velocity. This means it measures how quickly an object's speed and/or direction is changing.

* Zero acceleration means the velocity is constant. This implies that the object is:

* Moving at a constant speed, and

* Moving in a straight line (constant direction).

Examples:

* A car traveling at a steady 60 mph on a straight highway has zero acceleration.

* A ball sitting on a table has zero acceleration. Even though it's not moving, its velocity isn't changing.

* A satellite in orbit around the Earth can have zero acceleration in some frames of reference, even though it's constantly moving.

Key point: Zero acceleration does not mean the object is stationary. It simply means its velocity isn't changing.