Growth
For there to be growth you need to let go of the old and accept the new.
When Korra had come to Republic City she had been told that she was an obnoxious and selfish girl who would use the title of the Avatar for her own advantage. What few wanted to acknowledge was that she had shown growth and matured.
She still possessed qualities that made her who she was. However, she had become a more caring and friendlier person. She, more often than not if not all the time, put everyone ahead of her. She tried her best to help people and the world. She cared about others and was not afraid to sacrifice herself to help those who needed her.
And sure she was not done growing but she was still in the process of such.
She was learning to realize that she was not just only the Avatar but also a human being; she was learning to not keep everything to herself and have others help her, to not carry the burden by herself, and she was also learning to accept that there will always be people out there who care for her and are willing to help her.
And she was grateful for that.