Realised P&L refers to the profit or loss when traders start to trade until they close their position. Normally Realised P&L includes the trading fees to be paid or received, and the funding fees to be paid or received.
Calculation of Realised P&L
Unrealised P&L is calculated by using Last Traded Price or Mark Price. This P&L keeps changing in the Active Order until you close your position.
Calculation of unrealised P&L