The speed of an object at rest is zero. When an object is at rest, it means it is not moving and its velocity is zero.
On the other hand, when an object is moving with a constant velocity, its speed remains constant. Velocity is a vector quantity that includes both the magnitude (speed) and direction of motion. If an object is moving with constant velocity, it means its speed remains unchanged, and its direction of motion remains constant over time.
So, if an object is moving with constant velocity, its speed will be a specific value, but that value will depend on the particular object and its motion. It could be any positive value, including zero if the object is at rest.