Stroke Rate is how long will it take to finish one full stroke cycle with both arms.
Faster stroke rate is one of the factors which improves your swim speed.
Finding the right balance between stroke length and stroke rate will make you swim faster.
Removing dead spots and pauses will improve the movement efficiently
Too low a stroke rate and your arms are moving over too slowly and you almost certainly have some big dead spots in your timing.
Too high a stroke rate shows your stroke technique is too short and needs lengthening
The stroke rate might be affected by swimming distance.
For distances of over 400 meters, the stroke rates may range from 1.2 Stroke/Cycle to around 2 Stroke/Cycle)