Here's a breakdown:

* Displacement: The change in position of an object. It's a vector quantity, meaning it has both magnitude (how far) and direction.

* Time: The duration over which the displacement occurs.

Formula:

```

Velocity (v) = Displacement (Δx) / Time (Δt)

```

Units:

* Velocity is usually measured in meters per second (m/s) or kilometers per hour (km/h).

Important Notes:

* Speed vs. Velocity: Speed is the rate at which an object moves, while velocity is the rate at which an object changes position. Speed is a scalar quantity (only magnitude), while velocity is a vector quantity (magnitude and direction).

* Average vs. Instantaneous Velocity: Average velocity is the overall change in position over a period of time. Instantaneous velocity is the velocity of an object at a specific moment in time.

Let me know if you'd like examples or further explanation!