The adjective "evil" can be translated as a noun phrase. Alternate translation: "you must remove from among the Israelites the person who does this evil thing" or "you must execute this evil person" (See: [[rc://en/ta/man/jit/figs-nominaladj]])
The full meaning of this statement can be made explicit. Alternate translation: "will hear about what happened to the son and be afraid that the people will punish them also" (See: [[rc://en/ta/man/jit/figs-explicit]])