Performance by Percentile is showing the likelihood of a specific return and end value from the simulation runs.
Assuming the number of Monte Carlo runs is set to 1000, the 1000 simulations are grouped into percentiles. Stock Rover shows the annual return for each of the percentiles. Each of the bars represents two percentiles, as there are 50 bars. When the default of 1000 simulations is used, each of the 50 bars shows the median of 20 simulations in the percentile range.
The chart is showing the distribution of returns that you can expect for your portfolio along with the average return. Going from left to right the chart is showing the worst to the best-case scenario. The tooltip shows the annualized return, as well as the start and end value of the portfolio. The chart below is showing an 8.7% return in the 31st percentile, which means this portfolio has a 69% chance of at least returning 8.7%. The horizontal lines represent the portfolio(s) start value and the average ending value.
