In the Harry Potter film franchise - a sequence of movies based on the novels by the author J. K. Rowling - Fred Weasley does not die in the sixth film (Harry Potter and the Half-Blood Prince). The only notable death that occurs in this particular movie is that of Professor Dumbledore, as the plot of the film basically stays true to the events that happen in the book of the same name.
However, Fred Weasley does die in the seventh and final novel in the series, in the circumstances described below. (If you would prefer not to know how Fred's death occurs and to read the book or see the film for yourself instead, you might want to stop reading at this point!)
"'No -- no -- no!' someone was shouting. 'No! Fred! No!' And Percy was shaking his brother, and Ron was kneeling beside them, and Fred's eyes stared without seeing, the ghost of his last laugh still etched upon his face." - p637, Harry Potter and the Deathly Hallows
The seventh and last novel in the Harry Potter series was so long that two films were made from the book. The result of this is that Fred Weasley doesn't die until the eighth movie, Harry Potter and the Deathly Hallows: Part 2. His death occurs during the battle against Lord Voldemort on Hogwarts' grounds, and Fred is only one of many casualties including Remus, Tonks and Snape.