Hamlet has seven soliloquies in Hamlet. Their significance lies in their characterizing of Hamlet as an introspective and anguished character. While in a typical Renaissance revenge tragedy, a protagonist would quickly jump into action to try to avenge a death, Hamlet vacillates. Unlike Laertes, who is immediately out for blood when he learns that Hamlet has killed his father, Hamlet carefully contemplates his next steps and wishes he didn't have to face the problem of revenge. What, he wonders, if the ghost he meets has been sent by Satan to tempt him into killing an innocent man? How can he establish in some objective way that Claudius did, in fact, murder his father?
If Hamlet was already upset about his father death, the ghost's revelation sends him into a tailspin of depression. He indulges in suicidal ideation, wishing in his soliloquies that he could, for example, dissolve like the dew or take his own life, deciding that is only fear of what he might encounter after death that keeps him alive. He later ponders death as the great leveler.
Hamlet's contemplation of the meaning of life and death, largely through his many soliloquies, elevates this play from another entertaining bloodbath to a haunting meditation on universal questions about mortality, truth and purpose.