It is called a DuetDuet
He or she is usually called the Master of Ceremonies, otherwise known as the MC.
Keener
The song is called Venus As a Boy.
Jewel has many songs that are super popular within culture. One of her most popular songs is called 'Hands' and is the one that is the most played on the radio.
A group of three performers is typically called a trio.
troupe
duo
A group of performerstrio
People in the background are called Extras.
People in the background are called Extras.
mimes
A group of 5 performers who perform together is commonly referred to as a quintet.
There are many artists that have been known to sing the song 'My Valentine.' One of the most noted performers include Martina McBride, a popular country singer.
A group of performerstrio
It is called a DuetDuet
a quartet