What this tile shows
Squizzie calls this one Top referrers. It is a small table rather than a single figure, so it carries a few rows of detail on the tile itself.
Where the number comes from
Perkie Referrals. Referral counts, conversion rates, and top referrers.
What you need for it to appear
Nothing beyond Squizzie and the shop data it already reads.
The fuller picture
This is one figure out of a bigger subject. Loyalty reporting in Squizzie covers it properly.