How many million is a core?

Could you possibly clarify for me, how exactly do we convert the term "core" into millions? I'm rather puzzled about this unit of measurement in the context of finance or cryptocurrency. Is it a standard metric in the financial world? Or perhaps, is it a specialized term within the cryptocurrency community? Could you break it down for me, step by step, so I can understand how many millions constitute a "core"? I'm really interested in grasping this concept and its significance in the larger scheme of financial transactions.