A graduate of Colegio La Inmaculada Concepción in Manatí, Puerto Rico, she continued her studies at the University of Puerto Rico, where she obtained a Bachelor's Degree in Social Sciences, with specializations in Economics and Political Science.
In 1992 was selected as Speaker of the House of Representatives, being the first time in history that a woman held the highest position in the body.
[2] In May 2012, she became the center of a scandal when a photograph of politician Rafael Cox Alomar who was, at the time, the Popular Democratic Party's candidate for Resident Commissioner of Puerto Rico in the U.S. Congress was posted on her Twitter account comparing him to a chimpanzee and with the words "R.I.P.
Human rights defenders criticized Hernández for the personal attack against Cox Alomar, who is of Afro-Puerto Rican ancestry, however, in statement she claimed her Twitter account was hacked and that she did not post the offensive image.
She later apologized to Cox Alomar and terminated her Twitter account, promising to avoid social networks.