An electronic device comprising: a camera; a microphone; a display; a memory; and a processor (120; 300) configured to: receive an input for activating an intelligent agent service from a user while at least one application is executed, identify context information of the electronic device, control to acquire image information of the user through the camera based on the identified context information, detect movement of a user's lips included in the acquired image information to recognize a speech of the user, and perform a function corresponding to the recognized speech, wherein the processor is further configured to: control to receive a voice signal through the microphone; recognize a combination speech corresponding to a combination of the voice signal and the movement of lips; and perform a function corresponding to the recognized combination speech, and characterised in that the processor is further configured to, based on brightness of the acquired image information being lower than a preset value, display a user interface indicating failure of recognition of the movement of the lips to the user through the display. a camera; a microphone; a display; a memory; and a processor (120; 300) configured to: receive an input for activating an intelligent agent service from a user while at least one application is executed, identify context information of the electronic device, control to acquire image information of the user through the camera based on the identified context information, detect movement of a user's lips included in the acquired image information to recognize a speech of the user, and perform a function corresponding to the recognized speech, wherein the processor is further configured to: control to receive a voice signal through the microphone; recognize a combination speech corresponding to a combination of the voice signal and the movement of lips; and perform a function corresponding to the recognized combination speech, and characterised in that the processor is further configured to, based on brightness of the acquired image information being lower than a preset value, display a user interface indicating failure of recognition of the movement of the lips to the user through the display. receive an input for activating an intelligent agent service from a user while at least one application is executed, identify context information of the electronic device, control to acquire image information of the user through the camera based on the identified context information, detect movement of a user's lips included in the acquired image information to recognize a speech of the user, and perform a function corresponding to the recognized speech, wherein the processor is further configured to: control to receive a voice signal through the microphone; recognize a combination speech corresponding to a combination of the voice signal and the movement of lips; and perform a function corresponding to the recognized combination speech, and characterised in that the processor is further configured to, based on brightness of the acquired image information being lower than a preset value, display a user interface indicating failure of recognition of the movement of the lips to the user through the display. control to receive a voice signal through the microphone; recognize a combination speech corresponding to a combination of the voice signal and the movement of lips; and perform a function corresponding to the recognized combination speech, and characterised in that the processor is further configured to, based on brightness of the acquired image information being lower than a preset value, display a user interface indicating failure of recognition of the movement of the lips to the user through the display.