P&L stands for profit and loss.
Unrealized P&L
The profit or loss on positions you still hold. It moves with the market and isn't "locked in" until you sell the asset.
Strum shows it for the day and in total since you bought.
Realized P&L
The result on positions you've already sold. This is actual profit, not paper profit.
"Include sold"
By default, the portfolio composition shows only the assets you currently hold. Turn on "Include sold" to also see the result on positions you've sold.
"Where the profit came from"
On the "Statistics" tab, this block shows what added to your profit and what took away from it. It also shows how much of it went to fees.
Fees
Strum adds buy fees to a position's cost basis. So P&L already accounts for fees.