Two functions that an administrator should use when creating a validation rule are:
Error condition formula, which defines when an error should occur based on record fields and values Error message location, which specifies where on the page layout an error message should appear when triggered by an error condition formula Formula return type and rule active date are not functions used for validation rules. Reference: https://help.salesforce.com/s/articleView?id=sf.validation_rules_overview.htm&type=5