Brand signals are the factors and indicators that help the search engines and users identify the credibility and the reputation of any brand by its website. The credibility of the sites is built from many sources, like backlinks from authoritative sites, user reviews, social media content, and consistent branding across all the digital platforms of the brand.
They play a very important part in SEO, as many search engines consider the credibility of the websites to rank them higher in the SERP. A well-established brand is likely to rank better than a brand that is yet to build trust with its users.