A statement that tells you what should be done. These are specifically statements used in ethical contexts, where a statement may not be measurably true or false in any objective sense, but is still used as if it gives useful information.
"You shouldn't kill" is an example; Likewise "Don't kill", as the 'shouldn't' is implied. "Release the parking brake before driving" could be considered a normative statement, although since it doesn't give a moral or normative (in the sense of cultural norms) directive, it would not normally be referred to as one. (Taking off the parking brake would, objectively speaking, be a good idea in any culture).