"Women have light understanding" and "Extra understanding was given to women" - Why is there no contradiction?

Shalom, This is a good question, and there are several explanations: 

A. The Ritva in Tractate Niddah (60b) explained that the statement that Hashem granted women extra understanding more than men means that a woman’s understanding comes earlier in her life than a man's, not that she has inherently more understanding than a man. He wrote that this must be so in order to avoid contradiction with the sages who say that women's understanding is light. This is also clarified in the Tosafot of the Ra’ah on Niddah there, as well as explained by the Yafeh Toar and Etz Yosef on the Midrash (Bereishit Rabbah 18:1), and in the book Benihood Niddah there. 

B. In Iyunei Yaakov on Niddah, it is explained that before the woman was cursed, she was given extra understanding. However, after she sinned—and a person does not sin until a spirit of folly enters him—her understanding was taken away. Please see there for his words. C. Torah Temimah (Bereishit 2:39) wrote that there is no contradiction here, for the faculties of understanding (bina) and knowledge (da’at) are different. Da’at is the first intellectual grasp, while bina is the diligence of the intellect that follows contemplation. See also Torah Temimah (Devarim 11:48). 

Blessings, Hillel Meirs