Yellow = losing, blue = winning. They count what you'd get if you closed right now: every fee (paid and still to pay), the spread, slippage through the order book, and funding.
Each ball holds the same amount of USDT (shown under the tube). The top ball fills up first; the next ball appears the moment the loss or gain goes past a full ball. A fast wick drops them in one after another.
No balls = break-even. Close then and your balance is exactly what it was before the trade, to the cent.
Fees: taker -- · maker --