Reading the statistics
Loads, views, clicks and CTR – for the blocks on your site and for your content on other sites.
The exchange is measured from two sides, and the dashboard has a page for each.
Statistics → Clients is about your own site: how the blocks you placed performed in front of your visitors. Statistics → Content is the other direction: how the content you offered performed on other members' sites.
The four figures
Both pages show the same set: Loads – how many times a block was loaded, Views – how many times it was actually seen, Clicks – how many times a visitor followed it, and CTR – clicks as a share of views.
Each figure sits in its own tile with a checkbox that adds or removes the matching line from the chart below, which is handy when one metric dwarfs the rest.
Filters
Period switches between Last 24 hours, Last 7 days, Last 30 days and Last 12 months. Client narrows everything down to one of your sites, or keeps All of them together.
In the WordPress plugin
The plugin carries a short version of the same thing on its Statistics page: two seven-day charts with no filters, and a More details link under each that opens the matching page here – see Dashboard and Statistics in the plugin.