How much core is 1 billion?

Excuse me, could you please clarify something for me? I'm trying to wrap my head around the concept of cryptocurrency valuation. When someone says '1 billion cores', how much is that in terms of actual value? Is it equivalent to a certain amount of dollars, euros, or another fiat currency? Or is it a relative measure based on the market capitalization of a particular cryptocurrency? I'm just trying to get a sense of the scale and impact of such a large number in the context of the crypto world.