It is not known if there will be an actual, playable Valentina Kerman kerbonaut predefined like the original three, a non-playable character like those at the Kerbal Space Center, or if she is just the prototype of random female kerbals like those hired in the Astronaut Complex.
In real life, the first woman in space was Valentina Tereskova (Russian: Валенти́на Терешко́ва). Valentina Kerman, as the first female Kerbal, is almost certainly a nod to her.
At age 26, Tereskova flew aboard Vostok 6 from the USSR on 16 June 1963, logging a then-record 48 orbits within three days. For 19 years, she also remained the only woman to have flown in space.
In 2013, at age 76, she said she was willing to take a one-way trip to Mars.