Domain authority, or DA, is a third-party metric created by a company called “Moz” to approximate how high your website will rank in SERPs. DA ranges on a scale of 0-100. Numbers closer to 100 indicate that the website is likely to rank well in SERPs, and lower numbers indicate that the website is not likely to rank well. DA is not a ranking factor in Google and has no effect on SERPs -- it’s simply for SEOs, webmasters, marketers, and others to get a sense for how powerful the website likely is in a search engine’s eyes.
Although DA is specific to Moz, other SEO-focused tools have their own, corollary metrics. Examples can be found below:
Authority (from SEMRush)
Domain (Ahrefs)
TrustFlow (Majestic)
There are many more terms that are used in SEO or website talk. The above are a few more common ones to get you started.