What's "Unemployment Rate: 8.6 percent"?
With whomever the available people numbers were recorded, those unemployed were calculated in a simple ratio, ''unemployed/total number'', and that value turned out to be 8.6%.
It means that the unemployment rate of the entire population in the United States is 8.6%
It's a percentage of working age people who aren't working. However a lot of those people aren't looking for a job.