Final answer:
Fortinbras is a foil to Hamlet by contrasting decisive action with Hamlet's indecision and contemplation in their respective quests for justice.
Step-by-step explanation:
In Shakespeare's Hamlet, Fortinbras serves as a foil to Hamlet in the way he takes decisive action, in contrast to Hamlet's own indecision and inaction. Where Hamlet is philosophical and contemplative, often caught up in his own thoughts and uncertainties, Fortinbras is portrayed as a man of action, who leads his army to reclaim land without hesitation. This contrast is evident in Hamlet's soliloquies, where he reflects on his uncertainties and perceived weaknesses, indicating that Fortinbras's decisive nature highlights Hamlet's procrastination and existential struggles.