The Guidance section of Repeat Customer Insights lists common objectives Shopify stores might have for an analytical app and provides advice on them. It acts as an index or table of contents for the app.
Using it you can quickly find a problem you've noticed in your store and what reports might have an answer for you.
For example if you're trying to figure out how your customer base has changed over the past year, it'll recommend using the Customer Grid and the historic views.
It's the best place to start with if you're unsure where to go next or when you're looking for new optimizations.