While I have never heard the term “women taking up space” before, my interpretation of it would be women in positions typically held by men. The first example that comes to my mind is Hillary Clinton running for president in 2016, since the election and especially the presidency has almost if not always been a position always held by men. I would assume that it feels powerful yet also stressful, as being one of if not the first in a position is obviously a large burden to carry.
I would say the one thing that has prevented women from “taking up space” would be traditional gender roles. You could also say that women have not taken up certain spaces due to said spaces being historically held by men, though that could also just relate back to traditional gender roles. Point is, it’s because of traditional gender roles. Girls being solely taught traditional femininity could lead them to be afraid to do anything else, more specifically anything “manly,” or “masculine.” I assume this to be true because I experienced the inverse when I was younger (I was assigned male at birth).