Thank you!
- A concerned millennial
The US government spends far more than it generates in revenue, which is called a deficit. The deficit is typically financed as debt and that debt becomes a financial instrument capable of restructuring, private ownership, and refinancing as secondary debt (debt on an existing debt).
We can fund it through debt that we have to pay back (eg, issuing government bonds), but we can also literally print money.
Printing money can have inflationary effects because money is worth just a tiny bit less when there is more of it. But in a downturn this is generally a less important concern. There's no really simple answer for when printing money is fine and at what levels and when it is not, particularly since it is not a settled topic. The recent consensus generally seems to be that printing money in recessions is good though.