Something vanishes when it changes from you being able to see it, to not being able to see it. Something might vanish quickly or gradually. The picture is of a wall vanishing into the fog. A similar word to vanish is disappear.
Something vibrates when it moves backwards and forwards very quickly. If something vibrates fast enough, it produces a musical note. Musical instruments work by making a part of them vibrate in some way. The picture is of a vibrating guitar string.
Voting is a way for a large group of people to come to an agreement about something. Everyone writes their decision on a piece of paper, then all the individual votes are counted up and the majority wins. Most people are familiar with voting for a President or Prime Minister at election time.