Foldable electronic device for controlling user interface and operating method thereof

There is provided a foldable electronic device controlling a UI, including: a first housing; a second housing; a hinge to which each of the first housing and the second housing is rotatably connected; a flexible display accommodated in the first housing and the second housing and visible in the first direction; a sub-display accommodated in the first housing and not accommodated in the second housing, the sub-display being visible in a second direction opposite to the first direction; a processor; and a memory storing instructions that, when executed by the processor, cause the foldable communication device to: execute an application; displaying a first execution screen corresponding to the application at a first display ratio via the sub-display based on folding of the first housing and the second housing relative to each other; based on expansion of the first housing and the second housing relative to each other, a change is made from displaying a first execution screen of the application via the sub-displa