Often we want to give message to user on filling some critical text fields, let’s take example of such a case here:

So, we want to achieve this we need to configure a business rule:

Go to Settings->Customizations->Customize the system->Entity->Business Rules and create a new rule as per below screen:

Put Condition as below:

Put Action as below:

Save and activate the business rule. Make sure the scope on top right corner is set to intended form:

This should start showing default text for you on the field. Hope it helps!