Burning Sea Points, also referred as BSP, is a currency to purchase items in Treasure Aisle (TA). One Burning Sea Note (BSN) contains 300 Burning Sea Points (BSP).
Burning Sea Notes can be bought for real money in the Burning Sea Note Store, at https://account.portalusgames.com/store
Burning Sea Points can, unlike Burning Sea Notes, NOT be traded.
This information is provided by the update that PotBS Wikia is undergoing, by Captain Vuur.