When viewing your analytics page, you will see the following...
Total deliveries which are the total number of newsletters delivered over the specific time range set.
Total opens which are the total number of times your newsletter has been opened. If a subscriber opens your email five different times then each open will be counted under the total open.
Unique opens which are the total number of subscribers who opened your newsletter at least once.
Total clicks which are the total number of clicks on links within your newsletter.
Total unique clicks which are the number of subscribers who clicked on links within your newsletter.