When creating your Custom Dashboards, you might want to take a look at an overview of your audience. To add this component, go to Insights > New Dashboard or select a previously created Custom Dashboard > Add Component > Audience Snapshot. For more info on creating Custom Dashboards check out this help desk article!
The Audience Snapshot component is a deep dive into your audience engagement separated into two sections. The top section is an overall summary of your audience, including overall engagement score, total audience size, and % personalized. The bottom section is related to your chosen reporting period. See your engagement score, the number of new subscribers, and the number of new unsubscribes in the timeframe selected.