Question about currency?

Most likely an obsolete 5000 Yuan paper money printed either by the Central Reserve Bank of China or Central Bank of China in the post-World War 2 period before the establishment of the People's Republic in 1949. These notes in circulated condition are easily available for around $2 price range just like what you have discovered on eBay. It may not be worth much, but it's definitely rich in history, circulating at a time of the Chinese Civil War between the Communist Party of China and the Kuomintang that ended in 1949 with the latter retreating to Taiwan island to form the Republic of China.

China has a history of hyperinflation and has often rectified this problem by releasing new Yuan currency with an extreme conversion rate.

such as 10,000:1 ratios, and in some cases even higher!

Unlike American currency, currency in China from 1950 is no longer valid. Not to mention that if it were, it would be worth virtually nothing.

From what I understand Yuan is not supposed to leave China. If you're in the U.S. chances are you can't convert it. It might also be considered "hot" {stolen from China} money. It could also be counterfeit, who knows?

So, it's only use would be as a collectors item here, unless you're going to China, or know someone going to China.