In this passage the Zohar explains the dual nature of Binah. Although it is female because it is reflective Mind, Binah is also male - that is, active - because it gives understanding. Unlike the dark and sorrowing Malchut, which is located on a lower level of existence, Binah is all Light, and therefore full of gladness.
Kabbalistically, the realm of Binah is a cosmic repository of spiritual Light. Touching this realm awakens the full Light of the Creator in our lives, producing great gladness in our hearts and souls. Connection to Binah is established when we make visual connection to the words that tell of these supernal wonders. Thus, the Light of Gladness and Happiness fills our souls, especially if we meditate to share the Light with others as we peruse these verses.