you have 9 players...3 in the out field, 4 in the in-field, the pitcher and the catcher.
13 defensive players
9 defensive players.
9 the pitcher catcher 1st base 2nd base 3rd base shortstop left field right field and center field
18 players from each team are allowed on the field at one time.
There are a total of 29 people on the field. 11 Offensive players 11 Defensive Players 7 Officials
The maximum number of players on the field at any one time is 13, nine defensive players including the pitcher, and four offensive players, one occupying each base and the hitter. The catcher, by the way, is the only defensive player allowed to be in position not in fair territory. If your questions refers to how many players are allowed in the "outfield" at any one time, the answer is there is no limit, all eight defensive players, including the catcher, if you so choose, may be positioned in the outfield. The only one not allowed is the pitcher, of course, who must pitch the ball to begin play.
In baseball the only defensive player allowed to be in foul territory is the catcher. Otherwise it's a fielders balk.
At any time, there are 9 defensive players and 1 to 4 offensive players on the field.