In one half inning, when a team bats, for each batter:
There is a minimum of 0 balls to 3 balls are there. There are 0 to 3 strikes. There is 1 hit. There are 3 outs recorded before switching to fielding.
The pitching of a baseball is called a ball, when it is pitched outside strike zone. A strike is when a batter misses a pitch hits in the foul zone or hits into the catcher.
So in one half inning, there are 0 to 9 balls possible. In one innings 0 to 18 balls.
if the question is about the number of different new balls that are used in an innings of a baseball match -- then:
It seems usually about 8 to 10 balls may be used during one inning. The balls which fall in the foul region, or into the spectators area are lost or often given to spectators.