Product means multiply the given numbers, so the product is 30.
One of the most common uses of product is to determine the area of a rectangle. In this case 6 could be the length and 5 the width. That would be 6 units by 5 units where the unit could be any measurement of length such as centimetre, inch, foot, yard, metre, mile, etc.
Another use of product is to work out the total weight or cost of a number of items or objects. For example, the cost of 6 items each priced at $5 would be $30. This is also the cost of 5 items each priced at $6.