Tone is an attribute of voice that conveys the attitude or emotional state of the speaker.  The same words spoken in different tones can convey different meanings.  For example, the words “That’s great” spoken in a friendly and enthusiastic tone convey a positive message.  The same words spoken in a sarcastic or frustrated tone can convey quite a different meaning.  Be aware of your tone of voice to be sure you are sending the message you want to send.