An SEO score is a measure of how well the user-facing and technical aspects of your website contribute to SEO and high rankings. There are many different ways of measuring SEO scores, but most look for the same key details.
Good SEO scores always include: search engine and user friendly URLs, technical quality, server responsiveness, indexability, user content quality, unique content, indexable meta-content, user friendly navigation, user friendly visuals and mobile optimisation.