Lady Macbeth shows her ambition for her husband to become king, but she's worried about whether he has what it takes to do what has to be done in order for this to happen. She says Macbeth is ambitious, but he doesn't have the cold-blooded desire to do whatever is necessary for him to become king. She says his nature is "too full of the milk of human kindness. . ." to committ murder. Lady Macbeth can't wait for him to come home so she can convince him that he must do any and everything to become king. She remarks that even fate and the supernatural forces want him to become king.
Enotes has wonderful side-by-side texts of many Shakespeare plays. They show the original text and a modern translation. Below is the modern translation for the passage you did not understand. What Lady Macbeth is saying is a "prayer" of sorts, but not to any Christian god. She is asking the spirits to remove any womanly feelings from her and make her cruel enough to do anything necessary--including murder--to help her husband become king.
The raven himself is hoarse
With croaking about the fatal entrance of Duncan
Under my castle walls. Come, you spirits
That hear mortal thoughts, take away my womanhood;
And fill me, from my head to my toes, full
Of most terrible cruelty! Make my blood thick,
Stop up the ways remorse can get into and leave my body,
That no feelings of guilt
Keep me from what I intend to do, or put guilt between
The consequences and the deed! Come to my woman's breasts,
And make my milk poisonous, you murdering ministers,
Wherever in your blind shadows
You wait on human mischief! Come, thick night,
And rot in the most gloomy smoke of hell so
That my sharp knife doesn’t see the wound it makes
Or that heaven peeps through the blanket of the dark
To cry, "Stop, stop!"
To see the entire modern translation, click the link below:
For the complete translation of Act 1, Scene 5, go to E-notes side by side translation: An excerpt of the passage translated to modern version:
“The witches met me on the day of my victory in battle, and I have since learned that they have supernatural knowledge. When I tried desperately to question them further, they vanished into thin air. While I stood spellbound, messengers from the king arrived and greeted me as the thane of Cawdor, which is precisely how the weird sisters had saluted me before calling me 'the future king!' I thought I should tell you this news, my dearest partner in greatness, so that you could rejoice along with me about the greatness that is promised to us. Keep it secret, and farewell.”
(she looks up from the letter) You are thane of Glamis and Cawdor, and you're going to be king, just like you were promised. But I worry about whether or not you have what it takes to seize the crown. You are too full of the milk of human kindness to strike aggressively at your first opportunity. You want to be powerful, and you don't lack ambition, but you don't have the mean streak that these things call for. The things you want to do, you want to do like a good man. You don't want to cheat, yet you want what doesn't belong to you. There's something you want, but you're afraid to do what you need to do to get it. You want it to be done for you. Hurry home so I can persuade you and talk you out of whatever's keeping you from going after the crown. After all, fate and witchcraft both seem to want you to be king.