It means “The act itself does not constitute guilt unless done with a guilty intent”
Actus rea and Mens rea are the two necessary elements for the commission of any crime. The term “actus rea” means the body is guilty and the term “mens rea” means the mind is guilty. A guilty mind or guilty intention is important to prove the guilt of the accused. There must be a vicious will or malice intention as well as an unlawful act for the commission of an offense.
In the case: state of Maharastra v. Mayor Hans George, the Apex Court had held that the commission of an act is not a crime unless it is done with a specific guilty mind.