Final answer:
Fortinbras's importance for Hamlet lies in serving as a foil for Hamlet's inaction and indecisiveness.
Step-by-step explanation:
Fortinbras's importance for Hamlet lies in the fact that he serves as a foil for Hamlet's inaction and indecisiveness. While Hamlet struggles with his own internal conflicts and is unable to take action, Fortinbras is portrayed as a decisive and proactive character. His determination to avenge his father's death and reclaim the lost territories of Norway contrasts with Hamlet's delay and hesitation.