The best solution here would be to first check the metric icon legend below the dashboard, which explains the symbols indicated in the KPIs overview of the dashboard.
Please NOTE that some KPIs (eg. reach, impressions) are available only for your own profiles with valid access permissions.
Also some KPIs (eg. fans-related KPIs: engagement, number of fans etc) start being calculated by Fanpage Karma only from the moment this page was added to our system (by you or any other user).
In case you are looking at cross-network KPIs, you should always pay attention that only the social networks marked in black can be analysed by this particular KPI. The ones that are blurred out are not available for this metric.