Non-Farm Payrolls measures the net change in the number of paid workers in the US, excluding farm employment, government employees, and a few other categories. It's released monthly and is one of the most closely watched employment indicators in the world, not just for the US dollar but for risk sentiment broadly, since the US labour market is treated as a bellwether for the global economy.
What usually moves the dollar isn't the payrolls number alone — it's the combination of the headline figure, the unemployment rate released alongside it, and average hourly earnings (a wage-growth proxy that feeds directly into the Fed's inflation calculus). A strong payrolls print with rising wages reads very differently to markets than a strong print with flat wages.