How much is a fon?

Excuse me, I'm a bit of a novice in the world of cryptocurrencies and finance. Could you please elaborate on this unit called a "fon"? Is it a widely accepted measurement of value within the cryptocurrency space? Or perhaps, it's a niche terminology within a specific crypto exchange? Additionally, could you provide a rough estimate of its equivalent value in more commonly known currencies, such as the US dollar or Bitcoin? I'm curious to understand its significance and how it fits into the broader financial landscape. Thank you for your time and assistance in clarifying this matter.