Microsoft Purview is a group of Microsoft 365 tools that helps organizations understand, protect, and manage information.
It includes features related to data classification, sensitivity labels, Data Loss Prevention, retention, eDiscovery, and compliance.
For a small business, the most useful starting point may be identifying sensitive information and controlling how it is shared.
For example, a company can label confidential documents, warn users when sensitive data is emailed outside the organization, or keep certain records for a required period of time.
Purview can become complex because it covers many different information governance and compliance needs.
The best approach is to begin with business requirements. Decide what information needs special protection, how long records should be kept, and who is allowed to share them.
Technology should support those rules rather than creating rules simply because a feature exists.