In the Sacrament of Holy Orders, or Ordination, the priest being ordained vows to lead other Catholics by bringing them the sacraments (especially the Eucharist), by proclaiming the Gospel, and by providing other means to holiness. 

The Sacrament of Holy Orders (Ordination) is for those men who are studying towards the Priesthood or the Permanent Deaconate.  Priests to be ordain must be 25 years or older and within the Latin Rite of the Roman Catholic Church can not be married.  A Permanent Deacon (at least the age of 35) can be married if he is married prior to being ordained a Deacon.