Poetry uses forms and conventions to suggest differential interpretation to words, or to evoke emotive responses. Devices such as assonance, alliteration, onomatopoeia and rhythm are sometimes used to achieve musical or incantatory effects.
The average speed of an object tells you the (average) rate at which it covers distance. If a car's average speed is 65 miles per hour, this means that the car's position will change (on the average) by 65 miles each hour.
Average speed is the rate of change of distance with time. Average velocity is the rate of change of displacement with time. Instantaneous speed is the first derivative of distance with respect to time. Instantaneous velocity is the first derivative of displacement with respect to time.