Required

With the Required property you make it obligatory for a field to be filled in when users add Records. Users won't be able to save their Record unless they fill in the field(s) marked as Required.

Make sure you assign this property only to fields that the users can definitely fill in.

You cannot check the property "Required" and "Hide from entry" at the same time.

If you make a Subform required, please note the following:

When importing records to a Form that has a Required Subform, the system will not prevent new records from being imported to the Form if there are no Records for the Subform. Records to the Subform need to be imported in a second step.
The system does not prevent records of a required Subform from being deleted. So even if a Subform is Required, its records can be deleted.
Make sure that the fields added to a Required Subform can be filled in during data entry. For example, a Subform that consists only of fields with Relevance rules or the 'Hide from entry' property checked might prevent a user from saving a record altogether.