Belle
Scrooge sees Belle, a woman he loved, as he's visiting the past. Belle is a symbol of the love he had and which he chose to walk away from for money. This becomes a choice that he greatly regrets.
Tiny Tim
Tiny Tim is Bob Cratchit's son. He's sick and will not last another year because of the poverty the family lives in. Tim is a symbol of the children all over the world who are in need of help in order to have a chance to live, that their well-being is dependent on the community of people who can provide support, and Scrooge is that community member.
Future
We see Scrooge's death and it looks lonely and bleak. It is a symbol of the reality that awaits Scrooge if he continues on his path of cruelty and bitterness towards everything and everyone in the world.
Awakened
Scrooge awakens from his night of being taken through his life with the Ghosts. This single moment of being seen jolted from his sleep is a symbol that Scrooge has been galvanized out of his state of being one of the living dead and has finally arisen as a man with meaning in his heart and purpose to connect with others in a lasting way.
Hope
Dickens, the narrator of the film, tells us that Scrooge became a secondary father to Tiny Tim and that Tim lived. This snippet into the changed future is a symbol of hope for all of us to have when we choose to act with love and generosity towards each other.