understanding the data model for the Api access?

I am able to grab the data programmatically from the netdata api endpoint with no much problem.
interpreting the meaning of the parameters, like ‘points’, ‘before’, ‘after’ and ‘group’ is not very easy though.
I know there’s documentation here Database queries/lookup | Learn Netdata, but I struggle to make the mental model of how the date is stored internally and how it is presented through the Api.
for example ‘group’ is documented as “The grouping method to use when reducing the points the database has.”, yeah, it could be probably be mean, median, max etc. but over what period?

anyone can help to clarify how to think about the data for each chart?

We are working on a visual component to be part of the chart itself to explain how data querying works in more detail.

For now I can point you to this doc Netdata Charts | Learn Netdata and this video https://youtu.be/T5N_03NV9Ac?si=fnCJlMd5Wc8w1vIK