should Focus KW on Wordpress be one keyword or multiple keywords?

[Jake]

It's good to have a primary subject/theme for a site which can help search engines as well as users better understand what they will find on the site, but a single keyword is usually too narrow a focus, (one exception are micro niche sites that may use an exact keyword matching domain name, very effective at one time adjustments are probably being made to lower to the effect of such domain names,)
Commonly webmasters might research and compile a list of around 50 target keywords that they would like to rank for, often larger competing sites prevent your from effectively ranking for the ideal keyword like "Weight Loss", ranking for 'long tail' keywords like "Natural vegetarian weight loss diets" will have less competition, indicated in part by the number of results Google shows for a search, it's a common practice to feature a keyword from your shopping list in the meta title, header and body text of a page.