Indeed. All sports have their own language. It's equivalent to say 'play action' in American Football. No one outside the NFL has a clue what that means but to most American's it's obvious.
'Silly Mid-on' is a fielding position in cricket. You have the 'on side' and the 'off side'. I think the 'silly' part comes from the fact that it's a 'silly' position because it's so close to the batsman and it's very dangerous so you have to be 'silly' to field there. You also have 'mid on' and 'long on which are in the same line as each other but the 'mid' and 'long' depend on how close they are to the batsman. In very simplistic terms, 'silly' means very close, 'mid' is half way between the boundary and the batsman and 'long' means as far as possible (on the boundary). The skill and technique in cricket is far superior to that of Baseball. There's way more types of bowling which present different challenges both to bowler and batsman. Spin, off-breaks, leg-breaks, fast, in-swing, out-swing, bouncers, slower balls.... The possibilities are almost endless. Likewise, the different forms of the game depend on how it's played. Some games are very short and limited to only 20 hours each side where's other forms last up to 5 days (average of 90 overs per day). The principles are the same in terms of scoring, batting, bowling etc but it requires a different mindset for the players. Some batsman are much more suited to being aggressive whilst others are more defensive and the truly great players can adapt their style depending on the situation.
Baseball is such a watered down version in comparison. I accept that cricket can seem alien to begin with but it's well worth sticking with as it's far more intriguing than Baseball if you have an attention span longer than a gnat.