Can Ты help me? Музыка and Пение question!

So I've Опубликовано about four Видео of me Пение on YouTube and people have прокомментировал(-а) saying that I can hold a tone, what does hold a tone mean? If Ты want to see them look up giraffecutie123 . If Ты do watch them can Ты Комментарий telling me how I can improve? Thank Ты so so so so much!