A useful way to understand what this audit measures is to imagine reading your website with no context whatsoever. No knowledge of your industry, no assumption about what a company with your name might do, no ability to infer from the photography that you are probably a law firm. Only the words, the structure and whatever can be verified elsewhere.
Most websites become surprisingly opaque under that reading. The home page describes an approach rather than an offering. The services page lists categories whose meaning depends on sector knowledge. The about page describes values. Nowhere does the site state, in a sentence a machine could extract, that this organisation provides these specific services to these specific people in these specific places.
The audit identifies exactly where that breaks down, which is almost always more specific and more fixable than the general impression suggests.