Confusing Modifiers

First, because the organization's proper name includes a modifier, the Grammarly software will be confused no matter how you rewrite the sentence.

Second, you should be careful and use the organization's full and correct name -- Office to Monitor and Combat Trafficking in Persons

Third, why would such an organization stop victims?

Fourth, you can help clarify matters by using an introductory phrase to describe how many offices the organization has.

With offices in 132 counties, The Department of State's Office to Monitor and Combat Trafficking of Persons aims to protect victims, prevent trafficking, and prosecute traffickers.