What is the use of <lightning:recordViewForm > in Salesforce ?

A lightning:recordViewForm component enables you to display read-only record data with one or more fields and labels associated with that record. You can customize the form layout or provide custom rendering of record data.

To create read-only fields, use the lightning:outputField component inside lightning:recordViewForm.

lightning:recordViewForm requires a record ID to display the fields on the record. It doesn't require additional Apex controllers or Lightning Data Service to display record data. This component also takes care of field-level security and sharing for you, so users see only the data they have access to.