Are you talking about this exchange ?  https://www.binance.com/

Found that they have 0.10% trading fee and if you choose to pay in BNB than you can save upto 50% on that trading fee.

https://binance.zendesk.com/hc/en-us/articles/115000429332


However they promote themselves as trading platform with 0 fee, the only zero fee they have is in deposits.