It is generally used to point out that many of the stories pointed to by conservative media as exhibiting liberal bias are often simply reporting on facts that are incompatible with conservative talking points.
Examples include: relative sizes of inauguration crowds, whether China or US importers pay for tariffs, the contents of the Mueller report, crime statistics on undocumented immigrants, crime statistics on Muslim communities, merits of single-payer healthcare in other first-world countries, various statistics on gun crime, impact of republican vs. democratic presidents on government deficits, benefits (or lack thereof) of trickle-down economics/cutting corporate taxes, and the causes and mitigations of the US Great Recession that began in 2007/2008.