Determine refresh interval calculation in documentation

Dear Power BI Representative,

I am reviewing the 'Determine the Refresh Interval' section within https://docs.microsoft.com/en-us/power-bi/create-reports/desktop-automatic-page-refresh
There is a section determining the refresh interval with the following information
the direct query performance analyzer has 5 visuals with an estimate of 10 users = 50 queries
They say the data arrives at a rate of 2 seconds. Though I do not understand this measure.
I know a rate is usually a metric per something and I do not understand what those are here.
I also do not understand how the calculation is showing more load than the data source can support.  Please advise.

Thank you.