Composite is the headline, and it is the two others combined. Use it to track movement over time, not to compare yourself against a business in another industry. A plumber in Chicago and a SaaS company do not face the same questions.
Visibility
How often you are named across your tracked questions and engines, weighted by how prominently. Being cited as a source scores higher than being listed; being listed scores higher than being absent. This is the number that reflects your actual position in the market, and it is the slower one to move.
Readiness
How well your site is set up to be read. This one is entirely within your control and usually the fastest win. It is the number the Fix Pack is designed to move, often within a day of publishing the changes.
A low readiness score with a decent visibility score means you are being recommended despite your site, not because of it. That is the most improvable position there is.
The tier
Invisible, Emerging, Competitive or Leading. A plain-English band, so you can tell someone where you stand without quoting a number they have no reference for.