There are two forms of Brahman, the material and the immaterial, the mortal and the immortal, the solid and the fluid, sat (being) and tya (that), (i.e. sat-tya, true).

In plain words: Brahman, the ultimate reality, has two forms. One has shape, dies and is solid. The other has no shape, never dies and is flowing. Together they make up what is called "true."