Content Managers (more recently being referred to as Content Engineers) generate new content for an existing website or a new up-and-coming website in order to ensure that content is ready to be indexed by major search engines with selected keywords in mind.
Content is targeted towards the audience while also featuring keywords that are targeting search engines that index the pages of the website. Content managers participate in studies to ensure that their practices are capable of improving the relevance of a page to specific keywords.
Having professional content written accounts for grammatical and spelling issues that arise from content being written by someone without a professional history in content writing. See also a career in SEO Copywriting.