"Qualifying segments" refers to specific groups or categories within a larger population that have certain characteristics or meet certain criteria. Full definition
The new tier, Platinum Pro, falls between Platinum and Executive Platinum and requires 75,000 elite qualifying miles or 90 elite qualifying segments annually. (frequentbusinesstraveler.com)
That is the total miles, and total qualifying segments from the two programs will be added together in order to assess the status level for 2016. (austravelpoints.com)
Under the current system, you can qualify for elite status based on elite qualifying miles, elite qualifying points, or elite qualifying segments. (onemileatatime.boardingarea.com)