The terms SEO experts often start with are page authority (PA) and domain authority (DA). DA, a concept in fact coined by Moz, is a 100-point scale that predicts how well a website will rank on search engines. PA is the modern umbrella term for what started as Google's original PageRank algorithm, developed by co-founders Larry Page and Sergey Brin. Google still uses PageRank internally but has gradually stopped supporting the increasingly irrelevant metric, which it now rarely updates. PA is the custom metric each SEO vendor now calculates independently to gauge and rate (again, on a scale of 100) the link structure and authoritative strength of an individual page on any given domain. There is an SEO industry debate as to the validity of PA and DA, and how much influence the PageRank algorithm still holds in Google results (more on that in a bit), but outside of Google's own analytics, they're the most widely accepted metrics out there.
Ever heard of Maslow's hierarchy of needs? It's a theory of psychology that prioritizes the most fundamental human needs (like air, water, and physical safety) over more advanced needs (like esteem and social belonging). The theory is that you can't achieve the needs at the top without ensuring the more fundamental needs are met first. Love doesn't matter if you don't have food.