You want to sleep in, but the alarm is jangling loudly. Your body is filled with inertia. You have to force yourself to get up. Speed is how fast an object is moving. Speed is calculated by dividing the distance traveled by the time of the motion.
Velocity is speed in a certain direction.
You can run every which way but not get anywhere, unless you run in one direction. If you run with velocity you run in a certain direction. Acceleration is the change in speed during a certain period of time. If you put your foot on the accelerator, you will change your speed. That's positive acceleration.