A pip is the smallest movement a price can make. When you decide how much to risk, you do so in pips.
Example: Suppose you have 150 available pips and you decide to risk 10 pips on a new trade. Once you set the trade, your available pips will decrease to 140, as those 10 pips are now at risk.
If the trade hits the Take Profit (TP): The 10 pips you risked will be restored, and the profit pips will be added to your initial 150 pips. If the trade results in a 20-pip profit, your total available pips will increase to 170 (150 pips + 20 pips profit).
If the trade hits the Stop Loss (SL): You will lose the 10 pips you risked, reducing your total available pips to 140 (150 pips - 10 pips loss).
This method ensures that your available pips reflect the outcome of each trade, with successful trades increasing your total and losing trades decreasing it.