Customer Purchase Latency is a measurement of the delay between customer purchase events (orders). It's in the form of a time, usually a number of days. So a 30 day Customer Purchase Latency means 30 days pass between orders.
This is usually aggregated across all of your customers into Average Customer Purchase Latency.
Eric Davis
Get a complete view of your customer behavior
The cohort analysis in Repeat Customer Insights will automatically build cohorts for all of your customers. It has the ability to go back through your entire store history so you can get a complete view of your customer behavior.