According to an embodiment, an electronic device comprises: a memory and at least one processor operatively connected with the memory. The at least one processor is configured to: in response to a voice assistant application being executed, identify a pronunciation variant for which an amount of sound source data stored in the memory is less than a specified value among a plurality of pronunciation variants, identify a subject based on the identified pronunciation variant, obtain a question text corresponding to a word including the identified pronunciation variant among a plurality of words included in the subject, output a question speech corresponding to the question text, and receive an utterance after outputting the question speech.