Is Fahrenheit a temperature at which books burn? What does this have to do with the story?
Fahrenheit is a temperature scale invented by a scientist named Daniel Fahrenheit. What this has to do with the book is that it is a story about book burnings that are carried out by fireman who no longer put fires out, but start them.
"At 451 degrees Fahrenheit, paper will burn. Fire is a primary image in the book. In the work of the fireman, it is seen as a destructive force. It stamps out books and the freedom of thought that books represent."
451 is also the number on Guy Montag's helmet, it is his Fire Station number. He is a futuristic Fire Fighter who responds to calls to go and burn books that are discovered in people's homes. Books are no longer permitted in this society.
It is against the law to possess books, and if a call is made reporting a suspicion of book ownership, the Fireman respond and look for the books, then they pile them up and set them ablaze with their flame throwers, assisted by the fire hose which shoots kerosene, instead of water.