I do not post many videos of mezzo sopranos, partly because they do not get the lead parts in Operas. The leads go to sopranos, and the mezzos are witches, bitches, and britches (boys).
A mezzo soprano is a voice in between the soprano and contralto range. Not only is the mezzo voice a little deeper than the soprano, but it is a heavier sound. The soprano frequently has a lighter, brighter sound but the mezzo soprano’s voice is darker and weightier, but no less beautiful.
Here is Elina Garanca singing Una Voce Poco Fa, from the Barber of Seville. The piece is a joyful portrayal of a young girl in love who will kill anyone who gets in the way of her and her love.