Is there any importance for these terms in trading? How are they different from Last Traded Price?
This is also called the Bid Ask Price.
Best Sell Price
If you want to buy a particular stock, then you need check for the Best Sell price to see what is the best price the sellers are willing to offer you so that you can buy it from them.
Best Buy Price
If you want to sell a particular stock, then you need check for the Best Buy price to see what is the best price the Buyers are willing to offer you so that you can sell your stocks to them.
If you notice on NSE or BSE, the best sell price will always be higher than the best buy price. Also, the exchanges will list down the top five best buy and sell prices by default. This gives you a perspective on what the traders are bidding.
Last Traded Price is on what the trade got executed recently.
Best Buy/Sell prices are the next available price which you can actually buy/sell. It gives you an idea so that you can modify your pending limit order price to match with the best available price, if you want your trade to go through immediately. (rather than waiting).
Also combined with volumes, you can get a feel that how long you need to wait for your order to execute.
If you set a buy limit order at 45.1 rupees and If Current Market price is 45.5, and if you see the best available sell price as 45.2 with a volume of 60000 shares, you need to wait until the 60000 shares of someone else gets executedin order for your order at 45.1 to execute. In this situation if you modify your order to 45.25 then your order will get priority and will get executed immediately.