Whenever you add an Entity in your Bot Responses, you would see this term Entity Reprompt in the Entity settings section. Let us understand what Entity Reprompt is in this article.
Irrespective of what entity you add, every entity has a certain property based on which it accepts and stores values from the users. So, for example, the phone_number entity will accept a numeric value, and that value needs to be in 10 digits. Consider this as a condition put by this phone_number entity.
So, if a user enters any number less than 10 digits, or a number more than 10 digits, the bot would send a message to the user which will ask the user to recheck the number that he has entered and make appropriate corrections to it and that message is a Entity Reprompt Message.
In the above image, the bot asks the user to enter his phone number, and the user has entered a 5 digit number, which is inappropriate, and hence the bot sent an Entity Reprompt as " That doesn't seem to be right. Please enter a valid phone number", after which the user sent a 10 digit number, which got accepted by the bot, and the flow went ahead where the bot asked the user for his Order ID.
Note:
You cannot make edits to pre-existing entities from the settings. You can only make edits to the local entities that you have created explicitly.