This means the video is from a news publisher that is financed or funded by a national government, this notice is displayed on the video watch page to indicate the publisher is “funded in whole or in part" by that government.
But I thought YouTube is supposed to be unbiased...or in other words, it shouldn't be trying provide information that a specific news outlet is trustworthy or not. Why isn't there a disclaimer for channels that constantly clickbait others into watching their videos?