As he prepares to leave for France, Laertes warns his sister Ophelia not to fall for Hamlet, a young man whose passions will change, and a prince who must marry to preserve the "sanity and health" of the state.
Laertes worries about Ophelia's honor just as Hamlet worries about Gertrude's.
Ophelia promises, but sassily tells Laertes to listen to his own advice.
Inequality between men and women.
Polonius enters, scolds his son for taking so long, then immediately starts giving him long-winded advice about how to act: be sociable, but not vulgar; do not lend or borrow money; to your own self be true, and on and on… Finally, he lets Laertes leave.
Father/son talk here mirrors Claudius's with Hamlet—except Polonius isn't just trying to hide a secret.
Polonius asks Ophelia what she was talking about with Laertes. Ophelia answers: Hamlet. After Polonius asks her to explain, she says that Hamlet has expressed his love for her. Polonius tells her that Hamlet is pretending to love her in order to sleep with her, and forbids her to talk to him.
Polonius gave Laertes advice, but gives Ophelia orders: women in Denmark are expected to obey.
Ophelia promises to obey.
Just as Hamlet promised Gertrude.