I want the meaning of the business jargon that says "big hitter".
A "Big Hitter" is a very experienced or talented person, this is metaphor drawn from baseball.
This is what the Urban Dictionary says:
Big Hitter (1): one who carries a lot of weight and influence in the work that he/she does. A big hitter is noted for his respect among clients and the industry that he serves. This term is often used in investment banking and sales when referring to a top money-maker or deal-closer.
Eg: When the year-end numbers came in at Goldman, it was obvious that the big hitters in the healthcare M&A group would be well compensated.
Big Hitter (2): The man, one who is a straight up "playa- playa". One who cannot be touched. One who laughs inside at those who are unequal in the intellectual thought process. One who has a fat knot of cash in his pocket, or a fat accounts receivable with an extremely low day sales outstanding. One who can snap his fingers and have the world at his feet. One who can wine, dine, and 69. One who makes music that sounds like money. One who always have a big ole' stash of the best headies.
Eg: Damn, Adam is really a big hitter.