The Kite Runner is both a powerful story about redemption and family, and a catharsis for author Khaled Hosseini, who lived through some of the historical events detailed within. Amir, the protagonist, is guilty of betraying his friend (and half-brother) Hassan, and must redeem himself by saving Hassan's son. Through his actions, he discovers that family ties are more powerful than guilt and anger. Hosseini lived a similar life to Amir, although less dramatic, and included his own childhood friendships, displacement from Afghanistan, and settling in California; this allowed him to show non-Afghans some of the traumas and hardships that his people went through during the Soviet invasion.
When you ask what the work means, I assume you're asking about the theme of the story. I think there are a few -
Mr. Hosseini addresses the relationship between Amir and her father, and Amir's struggle to earn acceptance from his father.
It's also about atonement Amir trying to make amends for the wrongs he committed early on in his friendship with Hassan when he witnessed Hassan's assault and did nothing to help him.
The work is worthwhile because it addresses powerful themes in an extremely relevant setting that is currently at the center of the world's attention.