Right language simply means using terms and phrases in your website that are most commonly used by people when they type what they are looking for into a search engine. These phrases are also noted and collected by the search engines. The more friendly the copy in your web site is to the search engines, the more likely people are to find you (which of course increases your sales.) In addition, the more hits you get from people searching for your products or services the higher your web site will be indexed on the search engine pages.
Remember that everything is basically one big popularity contest. Essentially the more hits you have, the higher your ranking is in the search engines.
Launching a website without any type of SEO is like throwing a party and forgetting to invite people.