What this tile shows
Squizzie calls this one Avg Session Duration. It reads as a length of time.
Where the number comes from
Google Analytics. Traffic, sessions and conversions from your GA4 property, read through the Google Integrations hub.
What you need for it to appear
A connected Google Analytics property. Squizzie connects through the Google Integrations hub, so it is one sign-in rather than an API key.
The fuller picture
This is one figure out of a bigger subject. Google Analytics without the other tab covers it properly.