Understanding your MOZ score...
Posted by: Brett R. Smith
Rank - means on which page of google does your website rank for a particular keyword. Since SEO is all about getting on the first page of Google search results. You see 'not on first page' of SERP (Search engine page results). If a keyword is important to you, you want to be on the first page of Google search results for that keyword.
Difficulty - Keyword Difficulty is based on the PA (Page Authority) and DA(Domain Authority) scores of the results( web links) that rank in Google's top 10 for a given keyword, as well as several other factors (like how many homepages vs. internal pages appear, use of query terms in the results, and more). So what difficulty means is how difficult it is for your website to rank for that keyword on Page one of Google search results. A lower Difficulty score means it is easier to get in here.
Opportunity - So how Moz calculates the opportunity score is by looking at all the SERP features that appear in a set of results (e.g. an image block, AdWords ads, a featured snippet, or knowledge graph etc.) And then based on all this it calculates what is the expected percentage of clickthroughs for organic web results for that keyword on the SERP. If it shows a low opportunity score, it means even if you manage to get on the first page for that keyword, with so many other forms of information available on the page, the chances of getting a clickthrough is low. If it shows a higher opportunity score it means, for that keyword there are not many distractions ( non-organic SERP results, like Ads and Image Packs etc.) so chances giving you a better chance of ranking organically.
My score - Now there might be multiple keywords which have a similar opportunity or priority score. How do you choose which ones to go after? Some keywords might be easier to execute than others, so Moz gives you the option of prioritising the keywords you think are important to you. The score you give is added to the Priority score, making is easier for you to rank your keywords.
Priority - Keyword Priority (previously know as Potential) is a score out of 100 worked out by looking at all the other metrics, (Volume, Difficulty, Opportunity and Importance), and combining that data to provide a score out of 100. Higher Priority represents a sweet spot of higher Volume and lower Difficulty.
A good priority score is what you should look since it into account all the other factors.
Hope this makes it simpler to understand.