After Ace was hit by Akainu in the battle on top, his body was still conscious. When the red-haired man left with his white beard and Ace's body, Ace's body was suddenly involved in the turbulence of time and space by the time fruit user's ability. The time fruit user delayed Ace's body's time to even a stagnant state out of guilt, but it could only last seven days, so before that, Ace had to heal his injuries.
The content of the movie is Ace's journey five years later.
There are three timelines in reality (so there are three volumes). The content of the movie is the same, but because it is too long, in order to avoid confusing the timeline, I will write it separately.
The three timelines are when Luffy first went to sea, after the War on the Top, and after the Onigashima War.
Intent: The fruit of time cannot change the past, but it can create the future