Just to add a little background...
Hamlet speaks these words upon hearing that the watch has seen the ghost of his father. He thinks that it is a sign that something is wrong. Although he does not know of the murder of his father by Claudius, the appearance of the ghost is seen as a sign of unrest.
The notion behind the statement "Foul deeds will rise though all the earth will overwhelm them" is that even though they are buried deep, the truth will emerge, and people will know of the dark deed. Elizabethans would have believed that the ghost is a sign of wrongdoing, and that it rises because justice needs to be served so that the spirit can rest.
My father's spirit in arms. All is not well.
I doubt some foul play. Would the night were come!
Till then sit still, my soul. Foul deeds will rise,
Though all the earth o'erwhelm them, to men's eyes.
Hamlet is the speaker of this quote.
Hamlet was the speaker of the quote. He speaks these words at the end of Act I, Scene II:
Your loyalty, as mine to you. Goodbye.
My father's spirit in arms! All is not well,
I suspect some foul play. I wish the night were here now!
Until then, sit still, my soul. Wicked deeds will rise to be (modern translation)
,where he heard from Horatio that the watch, Marcellus and Bernardo encountered a strange apparition that looks like Hamlet's deceased father, which looks exactly from head to toe like him at night when they were patrolling the country. Hamlet find it very strange that the patrol could have spotted his long-dead father and felt that it could have been a warning that something bad might happen later on, maybe a sign of trouble.
The meaning of the wandering ghost lurking in the dark to most people is that the deceased person might have been framed or victimized to cause his agonized death, so the ghosts wants justice served on the person who makes his life a terrible one, so to leave the world in peace and harmony, he had to see some righteousness done that can see the criminal behind the bars or gotten killed, so the spiritual being symbolizes someone's wrongdoing or crime that causes a wrongful death of another, and that victim wants payback so that he can happily go to the netherworld and felt relieved that his death had been revenged.
By this statement "Until then, sit still, my soul. Wicked deeds will rise to be. Seen even if they are buried very deep in the earth.", it means that wicked deeds or wrongful acts would still surface out for people to expose even though it is buried deep in the earth.