It is after the Battle with Goku Black and Zamasu and you say your farewell to all your friends, you then get in the time machine and try to go back into the future but there is some sort of malfunction and you are teleported to another timeline where everything is different and looks somehow more futuristic. Meant to put this in others but I Don't own any of the characters. RWBY is owned by Rooster teeth and Trunks is owned by Akira Toriyama