The Sri Yantra expresses Advaita or non-duality, which includes the union of the Masculine and the Feminine Divine. Four upward triangles represent Shiva or the Masculine, which is potentiality, while five downward triangles symbolize the female embodiment of Shakti, from whom all creation is made.
Together the nine triangles are interlaced in such a way as to form 43 smaller triangles in a web symbolic of the entire cosmos or a womb symbolic of creation. The triangles are of various sizes and intersect with one another in various ways, creating three-dimensional patterns. In the middle is the power point (bindu), visualizing the highest, seeming elusive center from which the entire figure and the cosmos expand.
The Yantra is a way to express the form of the divine, but also serves as a vehicle. It moves the gaze and consciousness of the viewer into the center, where all consciousness as multiplicity resolves back into the One.
Based in part upon Wikipedia: Sri Yantra