The entire piece of writing is a symbolic allegory, where each thing that Woolf focuses on is symbolic of a real thing in actual society.
Take the two fictional universities that she writes about: Oxbridge and Fernham. Oxbridge is an all male campus and Fernham is an all female campus. That is not a fictional set up. Plenty of colleges were historically either a male campus or a female campus. And as much as it shouldn't be true, there were noticeable differences in the quality of those campuses.
The room itself is symbolic. For Woolf, a locked room gives her, women, people, etc. "the power to think for oneself." The character Mary laments that she can't find any decent histories about women or stories about women or novels written by women. Mary's conclusion is that she believes women haven't been able to produce anything of note because they haven't been allowed the privacy and opportunity to really dive into their OWN thoughts.
A third piece of symbolism is the bad food Mary eats at Fernham. It's so bad that she can't even think straight after eating there. Early on Woolf/Mary writes: "One cannot think well, love well, sleep well, if one has not dined well." After the bad meal, Mary thinks the following: "Now what food do we feed women artists upon? I asked, remembering, I suppose, that dinner of prunes and custard." Mary is telling her reader that of course women artists and authors haven't produced anything worthy, because the food that they are constantly consuming at these so-called learning institutions for women is so bad that it actually stifles the creative powers of women.