Your counterparty is the current market, new buyers. If the buyers want to get in the market at the time you want to get out, then they have to pay the market price. You are not tied to specific buyers and sellers. Your counterparty is whoever happens to be in the market at that time. They pay your 6%.
Trading Pair Advice from the Platform
So BTCUSD is a trading pair
in trading you always exchange something (BTC) for something (USD)
the last part is the advice from the platform what you could do with the specific pair. (in this case sell the first for the second)
this is my guess because we do not know the ...