The phrase "the righteous" refers to righteous people in general. Alternate translation: "Righteous people will rejoice when they see" (See: [[rc://en/ta/man/jit/figs-genericnoun]])
Getting one's feet wet by walking on blood is spoken of as washing the feet in blood. Alternate translation: "the righteous will make their feet wet in the blood of the wicked" or "the righteous will march on the blood of the wicked" (See: [[rc://en/ta/man/jit/figs-metaphor]])
This exaggeration expresses that a great number of wicked people will die. Alternate translation: "so many wicked people will die that when the righteous march on their blood, it will seem as if they could wash their feet in it" (See: [[rc://en/ta/man/jit/figs-metaphor]] and [[rc://en/ta/man/jit/figs-hyperbole]])