system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Baseball Signs

I just want the general basis, but here's some questions too. 

How do they work? 
What do the 10 or so different hand signs the catcher makes standing for?
How are they different from team to team? 
How come it isn't easier to steal signs with so many players getting traded and moving from team to team?
gpt
Simple answer is, it could mean a lot of different things. The idea of having signs like in baseball is so no one knows what your plan is. For example, say a team's sign for the bunt is to touch your belt. A coach may go through a bunch of different motions, touches, etc, touch his belt somewhere in the middle, and there is the sign. Those are normally for 3rd base coaches to the batter and/or baserunner, who will both look for the sign in between pitches. The catcher gives signs to the pitcher, normally putting down a certain amount of fingers to indicate what pitch to throw. A catcher can also give signs to the infield to indicate how they want to approach the situation defensively. For example, the catcher may touch different areas on his arm to let you know what to do in case a player steals. Team's signs vary, for example Team A's sign for steal may be a swipe down the arm, Team B's may be to touch the top of your head. A sign could also involve more complicated progressions, for example, the sign for a hit and run may be the coach has to touch his ear, hat, and elbow, in that order. 

To answer your question about why it isn't easier to steal signs, sometimes it actually is, although it is an unspoken courtesy in the majors to not steal the other team's signs. However, many teams change up their signs often, sometimes even every game.