Yes, the tennis ball shooting from the racket of the fiery Andre Agassi in the 90's is like a bullet from a gun; a straight ace, the opponent can't come any close. Ace or no ace, if you are just beginning to play the game of tennis, service is a very important part of your game.
When tennis balls start flying your way in the game of tennis you are going to want to know not only what to do with them but how to do whatever you are going to do the best that it can be done. That would be to hit the balls. As fast as that ball enters your court by the hand of your opponent is just as fast as you want to return it. This is how you win the game.