What does the quote "There's rosemary that's for remembrance. Pray, you love, remember" from Hamlet, act 4, scene 5 mean?

There are two possible answers to this question.  The first is that it means absolutely nothing.  At this point in the play, Ophelia has gone mad.  She goes about chanting nursery songs, random tidbits of information, giving people herbs and flowers, and just not making a whole lot of sense.  She has been manipulated into a rejection of Hamlet, who made her believe that he truly and deeply loved her, she has been left all alone by her brother as he goes off to pursue his own interests, and, said ex-boyfriend Hamlet has just randomly and violently killed her father.  So, she's had some things happen that push her sanity over the edge.  So while Hamlet gallivanting about pretending to be mad, Ophelia actually IS mad.  The rosemary quote is just one of many nonsensical items that she mumbles about.

The second possible answer is to look deeper into the play and try to attach meaning to what she says.  She could be referring to the fact that people need to remember her father; his death was quickly hushed up because Hamlet was the one that did it, and Claudius didn't want a scandal in his kingdom.  They quickly bury him and send Hamlet away without even a slap on the wrist.  If you look at it from Ophelia's point of view, that's pretty infuriating.  So, maybe this is her skewed way of voicing her frustration that no one does seem to remember.  So, if you think about what other possible meanings the theme of remembering could have in the play, you could come up with some other interpretations.  I hope that helps a bit; good luck!

What does the Hamlet quote "There's rosemary, that's for remembrance . . ." mean?

In act 4, scene 5, Ophelia is depicted as mentally unstable as she enters the scene singing fragments of songs about chaos, death, and unrequited love. Laertes then enters the scene and sees his mentally ill sister for the first time, which only exacerbates his rage. As Ophelia rambles incoherently, she shows Laertes her bundle of flowers and begins to distribute them among those in attendance. Ophelia gives her brother flowers and tells Laertes,

There’s rosemary, that’s for remembrance. Pray you, love, remember. And there is pansies, that’s for thoughts (Shakespeare, 4.5.151-153).

The flowers that Ophelia gives each character have symbolic meaning and correlate with each character's specific circumstance. Ophelia ends up giving her brother rosemary and pansies, which symbolize remembrance and thought. Ophelia is probably distributing the rosemary to Laertes as a token of her love for him. She may have already made up her mind to commit suicide, and she may want to give Laertes something to remember their close, affectionate relationship. Ophelia may also want her brother to remember her as a healthy, vibrant woman instead of a depressed, confused person in anguish.  Similar to the flowers Ophelia distributes, she too is delicate, fragile, and beautiful. In act 4, Scene 7, Gertrude announces that Ophelia drowned in a brook surrounded by beautiful flowers, which floated around her body.