Each row shows a subject whose Wikidata entity has a flag image attached
via P41. Click through to verify the image actually is the
subject's flag (not a logo, building photo, etc.), check the box, and
use the toolbar to generate a QuickStatements batch. Paste the result
into QuickStatements
to create the entities. After they're created and the next nightly
build runs, the new flag entities will appear in this site's grid.