Mohel

A mohel is a person who circumcises Jewish baby boys eight days after they are born. This is a practice of Jewish law ("Halakha"). 
Procedure.
A knife is traditionally used for this, but a clamp is now sometimes used instead. In Orthodox Judaism the mohel is male. However, some more progressive types of Judaism allow women to serve as a mohel. 
Event.
The event of the circumcision is called a "Brit milah", sometimes pronounced "bris" especially by Jews of European heritage whose ancestors spoke Yiddish. The mohel says prayers with the infant's family and guests, to welcome the baby boy into the Jewish religion.