What is the Summoners job? Why is he so unattractive? Whwn does he usally speak Latin Phrases and does he actually know Latin? How does he conduct business?

The Summoner works for the Church. He calls people before the church council to answer for their sins (adultery, heresy). The people he summons are all at risk for excommunication. He knows very little Latin, but uses the few words he knows in order that people will believe him knowledgeable. The Summoner is an unethical, dishonest drunk. 

The Summoner's physical appearance is discussed in Gradesaver's summary for the Prologue. His face is said to be fire-red and pimpled, with narrow eyes. He has a skin disease across his black brows, and his beard (which has hair falling out of it) and he is extremely lecherous. There is, the narrator tells us, no ointment or cure, or help him to remove his pimples.