Answer:
The author realizes that Heide is happy and satisfied with the life she has.
Step-by-step explanation:
Heide is an orphan girl who has a very difficult childhood. After the death of his parents, Heide went to live with his aunt who could not take care of her and then handed her over to his grandfather who was a grouchy old man who did not want Heide's company. Even with all the bad situations in his life, the author shows that Heide found happiness in little things and was happy with his situation. This is what the author wants to reveal in the sentence:
"How beautiful! How beautiful! Good-morning, grandfather!" cried Heidi, running out.