The film begins with the end. We see that Louise has a daughter who has gotten ill and does not recover. She has lost her child. Once we see this, the film moves forward by going backward in time to when Colonel Weber recruits Louise to interpret the Heptapod language. The undertone of the film is based on one question, "If you knew what would happen in the future would you change anything today?"
This is the what give Louise her motivation to go beyond her limits and the limits set by others in her life both professionally and personally. Because Louise has been granted this gift/curse she has been given a great power, and what she does with it can determine the fate of her world both in a global way and in an internal one as well. She has seen that her and General Shang meet and he thanks her for what she did to stop him from striking against the heptapods. And because she's seen this she has a responsibility to do with it what is necessary to save humanity from destruction before Shang launches missiles at the spaceships. She does this against the orders of the President of the United States, Government and the Military.
It is language that can change everything in our lives. We see how the misinterpretation of intent when translated incorrectly can literally cause war and the potential of the end of the human race, but when interpreted correctly it becomes a gift. Louise's character represents the necessity for people across cultures and national boundaries to be understood precisely as our very lives depend upon it.
As for the gift of perceiving the future for Louise's internal world, it becomes clear to her that she will have a choice to make once her and Ian get married. She will have to decide whether to have a child with him or not as she knows the tragedy of their daughter's death before she is ever born. Even still Louise chooses to have the child, not out of pain or punishment, but rather because this is our life. We cannot stop suffering from happening, but we can choose to love one another with the cards we've been dealt. That, as this film says, is the only choice we have.
