A cannon fires a shell. The shell moves upwards, slowing its vertical motion until it reaches the top of its trajectory and then accelerating again until it hits the ground. The picture shows the barrel of the cannon at 45o to the horizontal. At this angle the cannon ball will have the greatest range for a given muzzle velocity.
If the cannon ball is shot out faster it will go further but if the angle of the barrel is made either bigger or smaller the range gets less - pointing the cannon straight up means a zero range. The cannon ball goes straight up and comes straight down!