According to hamlet fortibras is an admirable man. how does the sight of fortinbras and his troops change hamlets attitude

Fortinbras is presented in the play as Hamlet's foil. This means that he is a character that embodies everything that Hamlet is not. Hamlet himself is aware of this. While Hamlet feels compelled to avenge his father's murder, he is plagued with indecision, and this leads him to delay taking action. On the other hand, Fortinbras is brave and decisive, and he is not scared to die in order to regain his father's holdings. Hamlet admires this attitude, and this is the thing that motivates him to be different and become more bold and decisive.

not concrete, existing in thought or as an idea but not having a physical or concrete existence