Nahum often wrote prophecy in the form of poetry. Hebrew poetry uses different kinds of parallelism. Here he continues to describe the destruction of Nineveh. (See: [[rc://en/ta/man/jit/writing-poetry]] and [[rc://en/ta/man/jit/figs-parallelism]])
Here the word "blood" represents bloodshed and refers to the people who have committed murder. Alternate translation: "the city full of murderers" (See: [[rc://en/ta/man/jit/figs-metonymy]])