The answer is: Her role has shown that women are starting to perform in jobs that have been traditionally reserved for men.
Marissa Mayer was chosen to be the CEO of a giant tech company called Yahoo in 2012.
At that time, the percentage of women who managed to achieve executive position in tech companies are around 7%. Very little to them able to get the CEO position in tech companies since its traditionally given to male executives. Since Yahoo was highly valued, Marissa Mayer has became an inspiration for other women who want to advance in tech industries.