What is the significance of this quote and what elemet does it portray?Oh, from this time forth, My thoughts be bloody, or be nothing worth! Act 4 Scene 4
In Shakespeare's Hamlet, the lines you ask about conclude Hamlet's "How all occasions do inform against me" soliloquy (Act 4.4).
Hamlet once again feels rebuked by events he witnesses. Similarly to when he feels rebuked by the actor's show of emotion when he is just giving a speech which really holds no significance for the actor (Act 2.2), Hamlet now reacts to the sight of Fortinbras leading his army to do battle for a worthless piece of land. If these men are willing to die for a worthless piece of land, Hamlet feels, he should be ashamed for not enacting his revenge when he has a noble father to avenge.
Hamlet is changed by the sight of Fortinbras and all that has come before, and the quote you sight is his announcement of that change. From that moment on, Hamlet's thoughts will be bloody (metaphor), full of death, and he will take action against Claudius.
...O, from this time forth,
My thoughts be bloody, or be nothing worth! (Act 4.4.65-66)
are Hamlet's urging to himself to act quickly to achieve his revenge, and signify, many commentators believe, a change in character for Hamlet.
Of course, Hamlet continues to be contemplative after these lines. He does not become unthinking, as, say, Laertes does, when he goes after Claudius. But he acts decisively to eliminate Ros. and Guil. as retribution, jumps into Ophelia's grave with Laertes, and immediately kills the king when the king is exposed at the close of the play. Hamlet, one can argue, does act more decisively from this point on.