Silvius begs his mistress, Phebe, not to scorn him and compares her to a hardhearted executioner. Rosalind and Celia enter, in their disguises as Ganymede and Aliena, along with Corin, just as Phebe cruelly mocks Silvius’s "poetic" language of love, and comments that though he says her eyes are murderous such a thing is impossible because eyes are incapable of inflicting harm. Silvius responds that the wounds of love are invisible and that some day she may know of them. She remains unpitying and tells him that, until she feels such invisible wounds, he ought not approach her again.
Phebe here is calling attention to and dismissing the exaggerated and unrealistic language of love (or what Touchstone in Act 3, Scene 3 referred to as the "feigning" associated with love). As she is not in love herself, she sees the things that those in love are saying as being ridiculous, as not making literal sense. Note also that Silvius and Phebe are playing out classic roles of the genre of pastoral love: the helpless, desperate male lover and the scornful beautiful female beloved.
Rosalind (as Ganymede) steps forward and interjects with an extended insult directed at Phebe: she accuses Phebe of being too plain to be so proud and of having an inflated ego because of Silvius’s infatuation. When “Ganymede” finishes, Phebe proclaims that she prefers “his” insults to Silvius’s praise. “Ganymede” realizes what is happening and tries to dissuade Phebe from falling in love with “him,” but it seems that Phebe’s fallen in love at first sight.
Rosalind's insult adds a twist to the pastoral love scene by pointing out that Phebe isn't actually pretty enough to play the role of scornful beloved (though Silvius, blinded by love, thinks she is). And now, suddenly, while Phebe just before scorned the senselessness of love, as soon as she herself is scorned Phebe herself falls into a foolish love, with the very person who has just insulted her. Phebe, in other words, has fallen into the same role that she was just mocking Silvius for playing.
After Rosalind and Celia leave, Phebe decides to keep Silvius around so she can talk to him about love. She gives a lengthy description of Ganymede’s attributes, equivocates on whether she loves or hates him, and then orders Silvius to deliver to Ganymede a taunting letter that she plans to write.
Phebe is cruel to employ her smitten and obedient admirer to help her win the love of another, though of course it's funny too.