The Theme of this song by Demi Lovato is - "When you say your "Fine" the only one who actually notices there's something wrong is your best friend." Which for me is another way of saying that receiving a friend is a message from God trying to send you hope, help, and protection.
My Interpretation of this song by Demi Lovato is that one of the most precious things in life is the gift of a friend/ protector. A friend will come in your life to help you through your lifetime. So you won't be alone at lonely times and you will experience the best life memories with your friend. Either if it's a classmate or a family member or even your dog or cat. Friends are there.