I’ve dealt with a similar challenge while working with Dynamics 365 CE, so here’s what I’ve found helpful:

Field Descriptions in Dynamics 365 CE
You can view field descriptions by going to Advanced Settings > Customizations > Customize the System > Entities > [Entity Name] > Fields. Select a field to see its description (if defined by the admin or developer).

Backend Database Identification
If you're using Dynamics 365 Online, it’s built on Dataverse (formerly Common Data Service).
For on-premise, the backend is typically Microsoft SQL Server.
List of Queried Tables
Use tools like XrmToolBox (especially the Metadata Browser or FetchXML Builder plugins) Plug-in Trace Logs or Power Platform Admin Center. These help track activity and identify frequently used tables.
Tables Created by Dynamics 365 Not in DB
Some tables are virtual or system-managed and may not appear directly in the backend database. These can be explored via the Dataverse Web API or the Power Platform SDK.
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Column Descriptions & Business Contex**t
The XrmToolBox’s Metadata Document Generator is very useful. It lets you export column descriptions, data types, and more—especially useful for documentation or business analysis.

For a more structured overview of Dynamics 365 architecture and services, I’d recommend checking this out: Microsoft Dynamics 365 Services. It provides solid foundational insight, especially if you’re bridging technical and business perspectives.