What Hamlet is contemplating in his most famous soliloquy (To be or not to be) is the nature of life and what he should do with it. He is thinking about whether he should end it all (kill himself) or continue living and fighting for his revenge. His father was killed by his own brother and he wants to avenge the king's death but he is unsure how to do it.
He is torn between these two decisions, leading him to be stuck and ultimately do nothing for a while because he is indecisive. On one hand, he can go after Claudius who murderer his father, but on the other hand, he understands that that is meaningless and it won't bring him anything. However, in the end, he finally makes a decision - to go through with his plan.
