This is actually a great movie.

Rating: 9/10 (3 February 2017)

*Spoiler Ahead* I have seen many movies where people can see future. This also does the same. But ...... a big but the screenplay could have been more engaging. I liked the story. And you need to stick to the entire movie to completely understand when this film is all about. This film reminded me of "Interstellar".
The signs actually symbols time loop. When ever Amy asks anything to the aliens they reply with a circle sign. At the end of the movie it means a snake eating itself symbol.... a time loop. All the time the aliens were trying to say what the gift they want to give the human race. Which is power to see future.
At start of the movie we see the future first where Amy's kid had cancer. After the aliens gave Amy the power to see future she saw what the message she told China president/official in phone. She sees glimpse of her future. She also sees that she wrote a book where she explained all the meaning of those signs. This way she knows what the signs actually meant in present.
This a huge time loop puzzle film. I think I will have to watch it again from start to solve all the puzzle.
Honestly I love to watch science fiction movies which challenge me to understand the plot. Films like Inception, Inderstellar, Predestination and this are such kind of film which is not for everybody to understand.
Please Do not stop making such movies.
Thanks.