Five stages: leads → contacts → customers → invoices sent → invoices paid.
The percentages do not follow a cohort
This is the most important thing about the page. Each stage is the all-time total of that kind of record — not the group that came from the stage before it.
So "lead to contact conversion" is really total contacts over total leads. A contact who was never a lead — entered by hand, say — still counts in the numerator.
Which means a rate can exceed 100%, and that is not a fault. Read these as ratios of volume, not as a group being tracked through the stages.
Trashed records are not counted
Leads and contacts that have been deleted — that is, sitting in the trash — count towards none of the stages.
Stage timings are matched on email
The average time between stages is worked out by matching on email — a lead and a contact sharing an address are treated as the same person.
So anyone recorded without an email, or who converted under a different one, is absent from these averages. Having no email is allowed in this system, so these numbers are based on part of the data rather than all of it.
Source is only about leads
The source table says how many leads each channel produced and how many of them became contacts — and it covers only the recent period, unlike the stages above it, which count all time.
A lead with no source recorded appears under "unknown", meaning it arrived by a route that did not record one, rather than that its origin is unknowable.