Samsung had previously made the Galaxy Nexus, which if you remember was a phone with a curved glass screen. This upcoming phone would presumably have a display that's actually curved.
The purpose isn't exactly clear-we're not going to go from our phones right now to twisty bendy phones overnight-but DJ Lee, Samsung's mobile business head of strategic marketing said at an Galaxy Note 3 event in Korea that:
"We plan to introduce a smartphone with a curved display in South Korea in October"
So who knows when (if at all) this curved phone will make it stateside. Remember though, Samsung has promised bendy phones