[iskander]

It's a tool for...atomically loaning and repaying large amounts of money. You can use that however you want, most typically for arbitrage to bring markets into equilibrium while earning a profit. The arbitrage isn't fundamentally different from what happens in traditional markets and flash-loan-like primitives are being developed outside of crypto.

(I don't know what the second question means or what your mental model of a "real" currency is)