If you went to a Beis Ya'akov, you might have learned that the Gra said that a woman observing tzeni'us (modesty) is the equivalent of a male learning Torah. In the worldview of the Vilna Gaon and today's yeshivos, that is high praise. There is nothing better for a man to do, no greater obligation and no better way to cling to the Almighty, than through learning Torah. This means that the highest obligation for a woman and the way she finds her way to God is through being modest. Right? Wrong.
The real statement is found in only one version of the Vilna Gaon's letter to his family while he was attempting to move to Israel. He wrote:
ותבלין שלו לזכרים עסק התורה ולנקבות הצניעותThe Vilna Gaon was speaking in terms of one specific aspect. The Gemara (Kiddushin 30b) quotes God as speaking to the Jews and saying that He created the evil inclination but created Torah as its antidote. Rashi (Bava Basra 16a sv. Torah) explains that the study of Torah ends thoughts of sinning. The Vilna Gaon states that just like being involved in the study of Torah cancels out the power of the evil inclination in men, being involved in modest behavior does the same for women.
The antidote [to the evil inclination] is involvement in Torah for men and for women, modesty
This is a much more limited concept than one might have otherwise thought.
(On this, see R. Betzalel Landau, Ha-Ga'on He-Chasid Mi-Vilna ch. 15 n. 21; R. Pesach Eliyahu Falk, Modesty - An Adornment for Life, p. 38.)