The “dual mandate” as it pertains to the Federal Reserve refers to its two primary objectives:

1. Promote maximum employment (ensuring as many people as possible are employed in a healthy economy.)
2. Maintain stable prices (inflation control) – keeping inflation low and stable to preserve the purchasing power of money.

Winfree is arguing for dropping the employment part of their duties and focusing on controlling inflation. The practical results of this could include more aggressive inflation control but at the cost of higher unemployment, slower economic growth, and reduced focus on job creation.

Full contextual analysis of Section 4.4: Federal Reserve here.