Your bio is your first introduction to the audience. It will be read by the host of the competition. This should be written in the voice of the third person. This means using your name and “he” or “she” instead of “I” or “me”. The bio should be 3 or 4 sentences about yourself and your music. You may use this as an opportunity to let the audience know something about yourself that you might not want to say to them, but you would still like them to know. For example, you can tell them about an award you have won (most likely music-related) or something traumatic in your life that made you turn to music. If you wish, you can tell them your age and how long you have been singing or making music. Give the audience a reason to love you before you ever open your mouth to sing.
You should prepare this before your performance and bring it with you where you will copy it to the Contestant Sign-In form at the venue.