
Francisco opens the play and establishes the world of the battlements — cold, watchful, and unsettled. He is the most minor of Hamlet's speaking characters, but his few lines do exactly what is needed: they make the opening darkness feel inhabited and real before the Ghost appears.
Francisco is the sentinel being relieved of his watch at the very opening of the play — the first character on stage, though Bernardo speaks first. His few lines establish the atmosphere immediately: it is cold, it is dark, he has not seen a mouse stirring, and he is glad to be relieved. He exits the play almost as soon as he enters it.
His significance is atmospheric rather than dramatic. He sets the tone of the battlements — the cold, the dark, the nervous alertness of men on night duty — and his brief exchange with Bernardo grounds the supernatural events that follow in the physical world of a real military watch.
Francisco wants to go home. He is cold, tired, and glad his watch is over. His motivations are the most human in the play.
Francisco is a common soldier doing his job on a cold night. He is not a complex figure, and the play does not ask him to be. His plainness is the point — the supernatural intrudes on an ordinary world, and Francisco is the emblem of that ordinary world.