Lower production costs can allow companies to charge lower prices make less profits sell fewer products

Lower production costs can allow companies to 
charge lower prices.

If you can produce something at a lower price, then this means that you can sell it at a lower price too, and still make the same amount of profits, while probably gaining more business.

You wouldn't make less profits because lower production costs allow for you to lower the retail price, and for more product to be sold.

You wouldn't sell fewer products, you would actually sell more products, because people are more willing to buy whatever it is that you are selling if the price is lower.

The law of supply and demand