Uniques:
 "Made from a real users" - these clicks represents the number of visitors who clicked on a tracking link or visited a webpage. We check that the IP from where the click came from is unique within last 30 minutes (this default time can be changed in the setting page).

 Spiders: "Not human clicks" - these are coming from robots or web-spiders (such as search engines crawlers, rss feed generators, validators, etc...).

 Conversions: "Goal !!!" - is when that click lead to the conversion. Someone clicked that link or visited that page and then purchased or subscribed.

 Non uniques:
 "Multiple clicks" - All other clicks. Practically are all the clicks made from the same person after the first click.