When wages are below the minimum, what specifically is the FLSA referring to?

The Fair Labor Standards Act

Wage laws as guided by the FLSA does provide a resource for employers to ensure compliance with the law.  There are always going to be employees that believe they should be paid more but this is not the intent of the FLSA. When wages are below the minimum, what specifically is the FLSA referring to? Are there other laws that may impact wage levels?