What brand positioning means
Al Ries and Jack Trout described the idea in "The Positioning Era Cometh", a three-part series published in Advertising Age in April and May 1972. Their argument: in an over-communicated society, a company has to create a "position" in the prospect's mind, one that takes into account its own strengths and weaknesses and those of its competitors as well. The word itself was not new, they wrote; it used to mean what the advertiser did to the product. Their book Positioning: The Battle for Your Mind followed in 1981.
Kevin Lane Keller linked the concept to brand image in 1993, in the Journal of Marketing: the associations consumers hold in memory alongside the brand name, which can be more or less strong, favourable and unique. The essence of positioning, he writes, is a sustainable competitive advantage that gives consumers a compelling reason to buy that particular brand rather than another.
Brand positioning is not the same as branding. Positioning is the decision: who the brand is for, what it is compared with and how it differs. Branding is the work that turns that decision into a name, a visual identity, a tone of voice and an experience. Nor is it the same as brand awareness. Awareness says whether people know the brand; positioning says what they think of it compared with the alternatives. A brand can be widely known without anyone being able to say how it differs.
A page's position in search results, which is what SEO works on, is a different thing again. In Spanish both are called "posicionamiento", so Spanish-language sources need to be read with that in mind. Rankings can be tracked in Google Search Console; whether a brand position has landed can only be found out by asking people.