The settlement price is the price of a security that is quoted once the trading session of a particular exchange is over. 

There are two types of settlement prices: Daily settlement price and final settlement price.

• Daily Settlement Price: It is generally the weighted average price over the last 30 minutes of trading for the day for a particular security. For illiquid contracts where trading activity is not happening or was limited in the last half hour the settlement price is determined by the formula prescribed by the exchange. You can refer to this link in to find out the same for NSE.
• Final Settlement Price: It is the closing price of a security on the last trading day or expiry day of an F&O contract. This is the price at which the trades are finally settled between the buyers and sellers upon expiry depending upon whether the contract is cash-settled or physically settled.