Sometimes when users add Records they might not need to reply to all the questions of the Form. With this property you can customise when a field will appear in the Data Entry page. You can define under which conditions (rules) the field should appear to the user. This way you can save time and avoid confusion for users adding Records who don't need to fill in specific fields.
You can define various Relevance rules to customise when a field will appear. You can also write a Formula to define a more advanced rule.
The maximum number of Relevance rules that can be added to a field is 10.