Transcript
A threads post saying "There has never been another nation ever that has existed much beyond 250 years. Not a single one. America's 250th year is 2025. The next 4 years are gonna be pretty interesting considering everything that's already been said." It has a reply saying "My local pub is older than your country".
While the state of France goes back to the Franks under king Childerich in the late 400s, the modern nation of France evolved during the French revolution and the Napoleonic era.
The very idea of "nation" as a political entity build upon ethnicity instead of loyality to a ruler is younger than 250 years, so technically the claim that the US is one of the oldest, if not the oldest nation in the world is correct. I doubt though that the person OP quoted is aware of the meaning of the word nation other than a synonym for country.