In Act 3, Scene 2 (Lines 132-137), what does Juliet plan to do with the cords.
132 Take up those cords: poor ropes, you are beguiled,
133 Both you and I; for Romeo is exiled:
134 He made you for a highway to my bed;
135 But I, a maid, die maiden-widowed.
136 Come, cords, come, nurse; I'll to my wedding-bed;
137 And death, not Romeo, take my maidenhead!
I think Juliet is being a little like Romeo in his self-pitying melodramatic moods in this scene. I do not think she is truly planning to do anything bad to herself with the cords in this scene in the play - just entertaining 'drama-queen' notions like any teen now might at a certain stage in their development. Shakespeare shows in this how young and vulnerable both of the characters are, how un-developed in the ways of the world and adult life management. Juliet seems to think again quite quickly as she sends her Nurse on yet another errand. But the words "die maiden-widowed" are still foreshadowing what will happen to her at the end.
When she says these things, I do not believe that she is actually planning to do anything with the rope ladder. I think she is just being dramatic.
The rope ladder was supposed to be used to let Romeo come up to her room so they could sleep together. Now, she is saying, she is going to die and she will never sleep with any man. At this point, there is no reason to think she is going to die.
I suppose you could say she is going to kill herself with the cords, but that doesn't make sense. Just after she says the lines you cite, she gives the nurse a ring to bring to Romeo and tells the nurse to make sure Romeo comes to her room. So she's not planning to kill herself.