A device and method for providing a recommended sentence related to an utterance input of a user are provided. The method, performed by the device for providing a voice assistant service, includes determining whether the utterance input is a single utterance input; obtaining application history data related to the utterance input from among application history data representing an execution history of one or more applications executed by the user in the device when the utterance input is the single utterance input; generating the recommended utterance sentence related to the utterance input by using the utterance input and the obtained application history data; and outputting the generated recommended utterance sentence.