T (Trade Date): You place an order to buy or sell a stock, and the trade is executed.
T+1 (Settlement Date): The actual exchange of money and shares happens. If you bought a stock, the money is deducted, and the shares are added to your account. If you sold a stock, the shares leave your account, and you receive the money.
If you buy a stock on Monday, the settlement happens on Tuesday (assuming no holidays). If you sell on Friday, the settlement happens on Monday. T+1 is a faster settlement cycle that improves liquidity and reduces risk compared to the previous T+2 system (where settlement took two business days)."