How much data is a mega?

Excuse me, could you clarify for me the concept of a "mega" in terms of data? I'm a bit unclear on the exact measurement it represents. Is it related to the size of a computer file, perhaps? Or is it a unit of measurement used specifically in the realm of digital storage? I'd really appreciate it if you could break it down for me in simple terms. How much information, roughly speaking, does a "mega" of data encompass?