The government regularly spends more than it takes in from taxes by issuing bonds. People buy the bonds because the US government is considered quite safe. That in turn lets the government spend money, which ultimately makes its way into the economy as a whole. People use that money to hire workers, buy stocks, etc, making the economy look good.
But the Federal Reserve Bank has the ability to invent money for buying those bonds out of thin air. That means the bond prices stay high (and the interest rates low). That implies that the current strong economy is an illusion, and that's worrying.
The expected response of extra money being pushed into the economy without added value is inflation, and the inflation rate has crept up over 2%[1]. It's actually a little surprising that it has taken this long, since this is actually something they've been doing for over a decade. There is considerable debate about that, but it may be that the inflationary chickens are finally coming home to roost -- in which case things might get real bad real quick.
tl;dr: this indicates that the economy may not be as strong as we think, caused by economic manipulation by the Federal Reserve to make the economy seem stronger than it is.