What this tile shows
Squizzie calls this one Form Submissions. It reads as a single count.
Where the number comes from
Contact Forms. Submissions to the forms you choose, with your own test addresses left out.
What you need for it to appear
A supported contact form plugin. Squizzie counts Gravity Forms, Fluent Forms and Contact Form 7.
Charting
This one charts as well as tiles, so it can go on a report as a figure, as a graph, or as both.