Some Exchanges (Coinspot, HitBTC, etc) trade BNB on the "Binance Chain Network". You will notice that the addresses on the Binance Chain Network will start with "bnb". These tokens will not be able to be transferred directly to wallets like Metamask or TrustWallet without doing a conversion to the Binance Smart Chain. This page will cover the conversion process using the Binance Chrome Extension.