In act II, scene i of Shakespeare's Much Ado About Nothing, immediately after Don Pedro has just succeeded in wooing Hero for Claudio and failed at winning Beatrice for himself, Don Pedro proposes to Claudio they undertake a challenge. To keep themselves entertained until Claudio's wedding day in a week's time, Don Pedro proposes that they try and get Benedick and Beatrice to marry each other.
Don Pedro proposes his plan in the following lines:
I will in the interim undertake one of Hercules' labours, which is, to bring Signior Benedick and the Lady Beatrice into a mountain of affection the one with the other. (319-321)
The phrase "Hercules' labours" is simply a metaphor, drawing an allusion to the most powerful Greek hero, to indicate how difficult he believes it will be to pair the couple. Don Pedro solicits the help of both Claudio and Hero to undertake the task.
In act III, scene iii, when they believe Benedick thinks he is all alone, Don Pedro, Leonato, and Claudio trick Benedick into believing Beatrice is in love with him by gossiping amongst themselves about how Beatrice has told Hero she's in love with him. In the next scene, Hero similarly tricks Beatrice by letting her overhear her gossiping with Ursula about Benedick's alleged proclamation that he loves Beatrice.