In Much Ado About Nothing by Shakespeare, what advice does Antonio give to Leonato?

If you are referring to Antonio's advice to Leonato in Act 5, Scene 1, Antonio advises Leonato to be patient and to make sure that the ones who have offended him suffer too.
Act 5, Scene 1 begins with Antonio telling Leonato to calm down. Basically, Leonato is in a state of extreme grief, and he is traumatized by questions surrounding Hero's chastity. So, Leonato is in no mood to listen to Antonio's advice. He tells Antonio to "cease" his "counsel," essentially stating that the only one who can comfort him will be someone who has gone through the exact same thing he has.
Leonato challenges Antonio to find him a father who can "Measure his woe the length and breadth" of his and "let it answer every strain for strain." He says that, if Antonio can find such a man, he will indeed listen to him and be patient. Since there is no such man, Leonato tells Antonio to cease with his advice. Leonato also asserts that most people think it is their duty to "speak patience / To those that wring under the load of sorrow," but he would rather do without such advice.
Antonio tells Leonato that he's no different from a child, and Leonato begs him to leave him alone. Then, Antonio gives Leonato a piece of advice that he agrees with: He tells Leonato not to suffer alone. Instead, he must make those who have hurt him suffer as well. Upon hearing this, Leonato asserts that Antonio " speak’st reason" and that he will make sure everyone who played a part in dishonoring Hero knows how she has been falsely accused.