A runs test allows the statistical testing of whether a series of price movements occurred by chance.
A run is defined as an uninterrupted sequence of the same observation. Ex : if the stock price increases 10 times in a row, then decreases 3 times, and then increases 4 times, we then say that we have three runs.
Since our z-score is not in the lower tail (nor is it in the upper tail), the runs we have witnessed are purely the product of chance.
If, on the other hand, we had obtained a z-score in the upper (2.5%) or lower (2.5%) tail, we would then be 95% certain that this specific occurrence of runs didn’t happen by chance. (Or that we just witnessed an extremely rare event)