How we cite our quotes:
[…] but you must fear,
His greatness weigh'd, his will is not his own;
For he himself is subject to his birth:
He may not, as unvalued persons do,
Carve for himself; for on his choice depends
The safety and health of this whole state;
And therefore must his choice be circumscribed
Unto the voice and yielding of that body
Whereof he is the head.
Laertes tells Ophelia that Hamlet can't marry who he wants to—he has to marry for the "safety" of the entire "state." And he's right. If you were rich and powerful in the 16th century, your marriage was an opportunity to forge strategic political, social, and economic alliances. In other words, Laertes insists that a marriage between Ophelia and Hamlet is impossible. Marrying for love? That was for the commoners.
[…] Then if he says he loves you,
It fits your wisdom so far to believe it
As he in his particular act and place
May give his saying deed; which is no further
Than the main voice of Denmark goes withal.
Then weigh what loss your honour may sustain,
If with too credent ear you list his songs,
Or lose your heart, or your chaste treasure open
To his unmaster'd
Here, Laertes tells Ophelia that, if she sleeps with Hamlet, she'll lose her honor. But this isn't a moral argument on the ethics of premarital sex. He's talking about the way Ophelia's chances for a future marriage could be compromised—which is literally a matter of life or death for a young woman.
I would not, in plain terms, from this time forth,
Have you so slander any moment leisure,
As to give words or talk with the Lord Hamlet.
Look to't, I charge you: come your ways.
I shall obey, my lord.
Ophelia isn't actually agreeing here; she's just acknowledging that she has to obey Polonius. Parents in this play (and in powerful families of the Early Modern period) weren't necessarily interested in helping their kids develop to their fullest potential, or whatever the helicopter parenting line is now; they saw their kids as pawns in the game of life.