Signification, as Lacan called it, is that allows us to say denotes the meaningfulness of something, (namely 'discourse', owing to his variety of psychoanalysis dealing with language, such that it is not merely dealing with mental processes of a subject, which was the case with Freud, but with Lacan it is semiotics where signs as conveyors of meaning play an imperative role.) Lacan uses the sentence plein de signification which in English would translate into full of meaning.[1] Thus, we might say "signification" is simply the means of expressing meaning.
Signification can be better understood by using an example from literature i.e. of Denotation and Connotation where Denotation of a word is its primary signification and Connotation the secondary, underlying or other signification. E.g. "Light" denotes rays required for luminosity, but it may connote knowledge, wisdom, etc. For example, “I am the light of the world. Whoever follows me will not walk in darkness, but will have the light of life.”[2] Another example would be lines from Upanishad also famously used in sphere of Indian education and advertisements: "तमसो मा ज्योतिर्गमय"[3] which translates into "Lead me from darkness to light".