Unit price is the cost of one unit of an item. That unit is a measure of some sort, a weight, a quantity or volume, a length, etc. In this case the unit is weight measured in pounds. The unit price enables us to work out the cost of any amount of the same item. So in this case, 10 pounds would cost 10×2.75=$27.50, and ½lb would cost about 2.75/2=$1.38 (about).
In many countries stores are required by law to show the unit price of their goods. For example, a 500-gram packet of cornflakes may show the unit price of a kilogram of cornflakes. Unit price of apples may be shown as the cost per kilogram, so by weighing one or more apples you can work out how much they will cost.
You can use the unit price to compare the prices of different sized packages of the same goods, so as to get the best value for your money. Usually, a larger packet will have a lower unit price than a smaller one, because the manufacturer saves a bit on packaging. A store might mark down a larger packet so as to encourage the shopper to buy it instead of a smaller one. Next time you go shopping, check out the unit prices to make sure you’re getting a good deal!