My guess would be someone who focus' on providing
SEO or Search Engine Opitmization services for clients.
Simply put, Search Engine Optimization is using specific keywords on your website to help the search engines find you.
The whole idea of
SEO is always changing and offering
SEO services can be a tricky services unless you have strong skills and knowledge about
SEO. In my opinion if you are providing great content and your readers and potential clients are finding useful and using a platform like WordPress most of your
SEO needs are taken care of for the average person or client.
That's my opinion on the whole thing, I'm sure others will have some thoughts