Light
When a particle is slowing down, its velocity is decreasing over time. This means that its speed is reducing or it might even come to rest at some point.
Velocity describes how fast an object's position changes with respect to time. It includes both the magnitude (speed) and direction.
Acceleration measures how quickly an object's velocity changes over time. If acceleration is negative, it indicates deceleration or slowing down.
Speed refers to the rate at which an object moves without considering its direction.