These two phrases are parallel. The writer describes Yahweh causing water to flow from the rock as if he turned the rock into water. (See: [[rc://en/ta/man/jit/figs-parallelism]] and [[rc://en/ta/man/jit/figs-metaphor]])
The verb may be supplied from the previous phrase. Alternate translation: "He turned the hard rock into a spring of water" (See: [[rc://en/ta/man/jit/figs-ellipsis]])