Split screen mode was implemented in Fortnite via update 11.30. It allows two console players to play together, in the same game, with a single screen. It's simply perfect for duo practice, especially on the eve of a major competition in this format such as the Winter Royale 2019.
The feature had suffered various problems over the past week, to the point of being disabled by Epic Games on December 12.
Fortunately, it has been reintroduced today thanks to a patch. It's time to call your friend or teammate: the Winter Royale literally starts tomorrow, and with an event dedicated to console players, there's no reason not to take a chance!