What does "BNB/<STAKE>" mean in the recommended option for pair_blacklist when trading on Binance?
Does <STAKE> work like a wildcard in pair_blacklist, or do I have to add each entry for each BNB/* pairs separately like this?
It means whatever market you're trading on, the most popular are BTC and USDT. So if you're trading on the BTC market, your stake is BTC and thus add BNB/BTC to your blacklist..

It's intended as a sample - you can add all BNB pairs - or you can just add the one in your stake currency, this is up to you.
There is however currently no wildcard support for either blacklist, nor whitelist.
Thanks @Theagainmen and @xmatthias for the quick reply. I'm closing this then.