Warning: This post will contain spoilers for the season two finale of The Flash.
After alluding to it in the actual show last season, The Flash star Grant Gustin has confirmed that the third season will follow the events of Flashpoint, to a certain extent.
Gustin tweeted that the season three premiere would be called Flashpoint and was quick to remind fans that, while the season will deal with similar themes present in Geoff Johns' popular DC comic from 2011, it wouldn't follow it exactly. Much of that has to do with the number of crossover that occur in the comic between DC's catalogue of characters, which simply can't happen on the CW because of licensing problems.
Flashpoint was the comic that kicked off the New 52 series for DC. In it, Barry Allen (a.k.a. The Flash) goes back in time to stop the murder of his mother. Fans of the show know this already happened at the end of the second season. Following the prevention of his mother's death, Allen awakens in a new universe where things are drastically different. For example, this is a world where Bruce Wayne has died and his parents lived.
Allen is the only one aware that the changes have occurred and eventually goes back in time to merge with his earlier self and try to undo what he's done. As Gustin pointed out, Flashpoint can't exist on television as it does in the comics, but he did add that what they have planned is just as big in its own way.
The Flash just wrapped its second season a few weeks ago, and the new season won't premiere until later this fall.