A “Free Text Reply” node requires the user to type a response to your question/prompt in order to continue the conversation. This is useful for gathering unique user input, like questions about your service, or a user's feedback.
An example of a free text node would prompt user response to the question “How was your experience using Instabot?”. In response, the user can provide their opinion by typing whatever they want (rather than selecting from a list of options).
This is how it will appear to the end user when viewing the node in the published Instabot: