What a quick win is
Most of the clicks from a Google search go to the first few results, which means a page at position 7 can earn several times more traffic just by climbing to position 4, without any new content or links to a brand new page. Those pages are the cheapest rankings a site will ever win, because Google already considers them relevant and only needs a reason to move them up. This tool finds them in your own Search Console data and puts them in the order that pays best.
How it decides
It reads the last 28 days of final Search Console data for web search, by page and by search, and sets aside two kinds of search first. Brand searches go, because changing a page cannot win them, and so do searches Google spreads across many pages of one section of your site, such as the same search on every city page, since no single page can take those either.
A page then qualifies in one of two ways. It either averages position 4 to 10 with at least 50 impressions, so a move of two or three places is worth having, or it averages position 11 to 20 with at least 100 impressions, which is enough demand to make reaching page one matter. The estimate of extra clicks always assumes that next realistic step, two or three places up and never into the top three, and it uses your own site's click rates wherever there is enough data to trust them.
The action for each page
For every page on the list, EghosaBot reads the live page and checks it against the search bringing it the most impressions. If the title does not mention that search, the action is to add it; if the title does but the H1 does not, it is the H1; if both do but the page's second biggest search has no heading of its own, it is a new section. When all of that is already in place, the next places come from internal links and depth, and the action says so. Pages whose click rate is well below what their position usually earns are flagged separately, because their problem is how they look in the results rather than where they rank.
Your Google data
The tool asks Google for your email address and read-only access to Search Console, and nothing else, and Google gives that access for one hour. That access is kept only in an encrypted cookie in your own browser, never on the server, and signing out cancels it at Google straight away. The tool cannot change anything in your Search Console. Your report keeps the numbers it shows, and it is deleted 90 days after it was made. The privacy policy has the details.