It’s percentage of the entire population, if you organized everyone from lowest to highest IQ, what percentage of the entire population would you need to include for them to be in the top. It’s a little clearer when a point of interest is near the top. E.G. “person is in the top 1% of people in terms of wealth.”
A less kind way to say it is ‘91% of people have a higher IQ than this person’.
I read explodicle’s comment as a reply to DeSantis who said “She has no role in this” in his rant.