(CNN) It's something that girls and young women in western countries can't imagine: missing school, even dropping out, because of their periods. Yet as many as half the girls in rural parts of Ethiopia miss school for reasons related to their periods -- and that can have a devastating effect on their education and the rest of their lives.

Freweini Mebrahtu has dedicated her life to keeping girls in school by designing a reusable menstrual pad and trying to end the cultural stigma around the issue -- and because of her work, she has been named the 2019 CNN Hero of the Year

"I don't even know what to say," Mebrahtu said when receiving the award. "I am so humbled and grateful for CNN ... this is for all the girls and women everywhere. Dignity for all."

Online voters selected Mebrahtu as the 2019 CNN Hero of the Year award from among the Top 10 CNN Heroes finalists

Mebrahtu -- who is from Ethiopia and studied chemical engineering in the US -- designed and patented a reusable menstrual pad in 2005. She and her team produce 750,000 reusable pads a year at her factory in Ethiopia. Nearly 800,000 girls and women have benefited from her work.

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