The final act of Hamlet, by William Shakespeare, begins with two gravediggers whom Shakespeare calls "clowns." They are intended to be a bit of comic relief before the final scene which is full of foul play and murder, and they do add some levity to the rather melancholy play. This talk of death and mortality at the beginning of Act V is a juxtaposition to the last scene in which death becomes real for nearly every main character in the novel. More importantly, this scene develops the conflict which already exists between Hamlet and Laertes caused by Hamlet's murder of Polonius.
As he and Horatio watch and listen to the clowns talk about the person for whom they are digging a grave, Hamlet realizes that the dead person must have committed suicide because this burial is going to be such a furtive affair. When the few mourners arrive with the body (Hamlet and Horatio are hidden), Hamlet is devastated to learn that it is Ophelia who died; he must also realize that he is to blame.
Ophelia's brother, Laertes, is distraught and jumps into the grave with her, proclaiming her sorrow. He also believes Hamlet is to blame for his siter's death. Laertes' display of grief is too much for Hamlet to bear, and he, too, proclaims that he loved Ophelia before joining Laertes in the grave. Given the fact that Laertes knows Hamlet killed Polonius (his father) and suspects that somehow Hamlet is responsible for Ophelia's death, it is not surprising that Laertes wants to kill Hamlet. He grabs Hamlet by the throat and says, "The devil take thy soul!" The men begin to fight until Claudius stops them.
Many things happen in this scene with the gravediggers which foreshadow events later in the act, but the scene specifically develops the conflict between Hamlet and Laertes. Soon Claudius will use this conflict to convince Laertes to poison Hamlet in a sword fight; Laertes would not have cooperated so quickly and easily without this scene at Ophelia's grave site. The sword fight between Hamlet and Laertes, the final conflict, leads directly to the deaths of Gertrude, Laertes, Claudius, and Hamlet.