Electronic device including flexible display and method of operating the same

An electronic device comprising:

• a housing including a first housing structure and a second housing structure, wherein the first housing structure is configured to move relative to the second housing structure;
• a battery;
• a flexible display comprising a first area and a second area extending from the first area, wherein the second area is disposed on the first housing structure visibly to a front face of the electronic device, wherein at least part of the second area is configured to be visible to the front of the electronic device and/or be inserted into the second housing structure based on movement of the first housing structure to change a size of a visible area to the front face of the electronic device;
• a sensor configured to identify information related to the size of the visible area of the flexible display;
• and
• a processor,
• wherein the processor is configured to:
• identify a first size of the visible area of the flexible display using the identified information received from the sensor,
• identify a state of the battery,
• when the identified state of the battery is less than or equal to a first threshold, control the flexible display to display at least one user interface based on the identified first size and the identified state of the battery, wherein the at least one user interface includes information related to a second size to be changeable from the first size and an available usage time and/or the battery saving corresponding to the second size,
• receive an input on the at least one user interface to change the first size into the second size,
• in response to the input, move the first housing structure to change the size of the visible area of the flexible display into the second size, and
• when the state of the battery is less than or equal to a second threshold less than the first threshold, control the electronic device to turn off.