Where do the 50 leads come from?
From Google Maps and each business's own website. Scout searches Maps for your trade in your city, reads each business's site for the email address it publishes and its About page for the owner's name, and checks the domain takes mail. Nothing is bought from a list, so your 50 are not the same 50 everyone else got.
Are the email addresses verified?
Not one by one. Every address was published by the business itself and its domain accepts mail, but run them through an email verifier before you send. Pipefire customers get every address verified before a single email goes out, because bounces hurt your sending domain.
What is the Google rank column?
Where each business appears on Google for the search its own customers type, such as "dentists austin". Fewer than 1 in 100 searchers click past page 1, so a business on page 3, or beyond page 10, is losing customers it can see for itself. That is the opening line of your cold email.