How to exchange foreign currencies?
It does not differ anyhow from trading cryptocurrencies:
Exchange happens instantly, and you see your updated account balances immediately. Note that SOL does not execute foreign currency exchange directly. USDs, EURs, NGNs etc are cryptocurrencies issued by SOL Wallet and backed by SOL funds in the same currencies, allowing you to trade those tokens at the interbank FX rates - instantly and without any hidden fees.