When a batter or runner is out, they lose their ability to score a run and must return to the dugout until their next turn at bat.
To signal an out, an umpire generally makes a fist with one hand, and then flexes that arm either upward, particularly on pop flies, or forward, particularly on routine plays at first base.
Home plate umpires often use a "punch-out" motion to signal a called strikeout.
The general exception is when a fielder loses possession of the ball because they attempt to throw it immediately after making the out.
Although pitchers seldom get credited with putouts, they are credited with their role in getting outs through various pitching statistics such as innings pitched (a measure of the number of outs made by the pitcher, used in calculating their ERA) and strikeouts.